Introduction

Samsung have not focused on the gaming monitor market for a while, but they are now back, having recently released their interesting CHG70 range. The line-up boasts an impressive list of modern specs and features and their aim is to offer something high end for gamers, with a whole host of features that help to meet their demands. The range offers a QHD 2560 x 1440 resolution which helps provide more detail than older 1920 x 1080 models, and certainly a welcome upgrade considering the size of one of the models, the 31.5" C32HG70. The new screens also support AMD FreeSync 2 which offers the familiar dynamic refresh rate benefits along with HDR gaming support. They have a native 144Hz refresh rate VA technology panel with a 1ms MPRT (Motion Picture Response Time) spec and a whole host of additional settings and extras for gaming needs. They also offer an extended colour space thanks to Quantum Dot technology, with Samsung using their "QLED" branding from the TV sector on this monitor range to signify this.

The C32HG70 is the largest of the current CHG70 models at 31.5" in size, but most of the spec and features remains identical from the 27" version as well. This 31.5" model has an integrated power supply and that appears to be the only real difference. It is the C32HG70 model that we have with us now for testing.

Before we get started we should mention the firmware on this screen. Samsung have made it possible for the user to quickly and easily update the firmware of the CHG70 models via a simple website download and a USB stick. This allows them to release small updates or bug fixes during the life of the monitor which is handy, as it's always a pain to need to return your screen to the manufacturer for this kind of thing should an issue arise. The US Samsung website has the latest firmware available for download along with instructions of how to do it (also covered in the user manual). We first of all updated to the latest firmware at the time of testing (v1013.0). It seems there have been quite a few firmware versions since original release as ours was actually originally on v1005.0). We know that the latest firmware extends the FreeSync range and makes some other minor undisclosed adjustments to improve performance.

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Specifications and Features

The following table gives detailed information about the specs of the screen as advertised:

The C32HG70 offers a decent range of modern connectivity options with 1x DisplayPort 1.4 and 2x HDMI 2.0b  connections offered. The digital interfaces are HDCP certified for encrypted content and the video cables are provided in the box for DisplayPort and HDMI which is handy. These are the latest interface versions which allow HDR support from external devices over HDMI, and from a PC via HDMI or DisplayPort.

The screen has an internal power supply and comes packaged with the power cable you need (note that the 27" C27HG70 has an external power supply). There are also 2x USB 3.0 ports located on the back of the screen with the video connections, one offering fast charging support. A headphone-out, mic in and mic out connection are also provided if you need them.

Below is a summary of the features and connections of the screen:

 

OSD Menu

Above: OSD control joystick on the back right hand side of the screen (left) and 3 buttons on bottom right hand edge (right). Click for larger versions

The OSD menu is controlled through a single joystick control located on the back of the screen on the right hand bottom area (when viewing from the front). There are also 3 additional buttons to press located on the bottom right hand edge of the screen.

The 3 pressable buttons on the bottom edge control the 3 user customised gaming preset modes, allowing you to quickly and easily switch between them. When you press them you are given a quick pop up confirming your active options as shown above, which is a nice visual reminder of how you have the screen set up. You can customise each of these gaming preset modes in the main OSD menu.

Pressing up/down on the joystick gives you quick access to the brightness/contrast/sharpness settings, while pressing right/left gives you quick access to the volume control.

Pressing the joystick button in brings up a small menu allowing you further quick access to the input selection (left) and Eye Saver mode (right). You can then access the main menu from here (up).

Going in to the main OSD menu brings up the rather futuristic looking menu software above. This is split in to 5 sections down the left hand side, with the options available in each section then shown on the right in the middle. A help explanation is then provided on the right hand side when you highlight any given option, explaining what it will do. That's a nice touch we thought. Your current active gaming settings are shown at the top as they were in the quick access to the gaming presets we saw before.

The 'game' section of the OSD menu has a whole host of options including the active refresh rate, black equalizer, response time, FreeSync, low input lag, aspect ratio control etc. Plenty to play with here, and we will test most of these later on in the review.

The picture section has various controls useful for calibration as shown above. Going in to the 'color' menu gives you settings for gamma, white point and the RGB channels as well.

The 'system' section has a few other useful settings including the local dimming function for when you are viewing HDR content.

The OSD menu was easy to navigate thanks to the joystick, and it felt pretty intuitive and easy to use. There was a good range of options to select from as well and the software was responsive and looked quite different, in a nice way.

  

Power Consumption

In terms of power consumption the manufacturer lists maximum usage of 78.0W, and <0.3W in standby. We carried out our normal tests to establish its power consumption ourselves.

Out of the box the screen used 63.6W at the default 100% brightness setting. Once calibrated the screen reached 35.8W consumption, and in standby it used only 0.6W. We have plotted these results below compared with other screens we have tested. The consumption is comparable to most of the other larger 30 - 34" sized screens we have tested as you might expect, with some of the smaller 25 - 27" screens drawing slightly less power (comparing the calibrated states). Those with wide gamut support like the Dell UP2718Q draw more power because of their different backlight units, despite being a smaller size.

Panel and Backlighting

Panel Part and Colour Depth

The Samsung C32HG70 features an Samsung LSM315DP01 SVA (VA-type) technology panel which is capable of producing 1.07 billion colours. This is achieved through an 8-bit colour depth with additional Frame Rate Control (FRC) stage added.

Screen Coating

The screen coating is a light anti-glare (AG) like other modern VA panels we have tested. Not semi-glossy like some older generation VA offerings, but nice and light in line with modern IPS screens as well. It retains its anti-glare properties to avoid too many unwanted reflections of a full glossy coating, but does not produce an too grainy or dirty an image that some thicker AG coatings can. There are no visible cross-hatching patterns evident.

Backlight Type and Colour Gamut

The screen uses a White-LED (W-LED) backlight unit which is standard in today's market. This helps reduce power consumption compared with older CCFL backlight units and brings about some environmental benefits as well. This is paired with a Quantum Dot film coating which provides an extended colour gamut beyond the typical 100% sRGB coverage of a W-LED backlight. Samsung refer to the backlight as QLED in their marketing to distinguish this use of Quantum Dot coating.

Quantum Dot is designed to help provide a more bright and vivid image for more closer to real life colours. This helps push the colour space of the screen up towards the now-popular DCI-P3 reference that is used for HDR displays in the market. This gives rise to the quoted 125% sRGB coverage, showing that it extends 25% beyond the typical 100% coverage a common W-LED backlight monitor would offer. This equates to around 95% DCI-P3 coverage according to the Samsung specs, helping deliver a wider colour gamut and also meet certain defined standards for HDR content. We will talk about that HDR support later on in the review. Quantum Dot is also a more cost effective and energy efficient way to extend the colour space of a monitor compared to wide gamut LED backlights. It might not offer quite the same wide gamut (e.g. the Dell UP2718Q with GB-r-LED backlight offers 146% sRGB) but it is a half-way house. It gives some boost to colours without adding a big cost to production and retail, which is well suited to multimedia movies and games.

Anyone wanting to work with wider colour spaces would need to consider wide gamut backlight screens. If you want to read more about colour spaces and gamut then please have a read of our detailed article.

Backlight Dimming and Flicker

We tested the screen to establish the methods used to control backlight dimming. Our in depth article talks in more details about a previously very common method used for this which is called Pulse Width Modulation (PWM). This in itself gives cause for concern to some users who have experienced eye strain, headaches and other symptoms as a result of the flickering backlight caused by this technology. We use a photosensor + oscilloscope system to measure backlight dimming control with a high level of accuracy and ease. These tests allow us to establish

1) Whether PWM is being used to control the backlight
2) The frequency and other characteristics at which this operates, if it is used
3) Whether a flicker may be introduced or potentially noticeable at certain settings

If PWM is used for backlight dimming, the higher the frequency, the less likely you are to see artefacts and flicker. The duty cycle (the time for which the backlight is on) is also important and the shorter the duty cycle, the more potential there is that you may see flicker. The other factor which can influence flicker is the amplitude of the PWM, measuring the difference in brightness output between the 'on' and 'off' states. Please remember that not every user would notice a flicker from a backlight using PWM, but it is something to be wary of. It is also a hard thing to quantify as it is very subjective when talking about whether a user may or may not experience the side effects.

100%                                                                                   70%

50%                                                                                   0%

Above scale = 1 horizontal grid = 5ms

At 100% brightness there is a basically constant voltage applied to the backlight as you might expect. Oddly, despite the screen being advertised as flicker-free we were disappointed to see typical PWM behaviour as you adjusted the brightness setting below 100%. By the time you reach down to 70% brightness there is a full off/on modulation of the backlight. This operated at a fairly low 340Hz frequency (regardless of your active refresh rate). The duty cycle (on time) is reduced as you lower the brightness setting down until you get to 20% brightness setting, and then at the lower end of the range the modulation is also then reduced. That is, the 'on' voltage is reduced to bring about a further reduction in perceived luminance. This use of PWM could potentially cause issues with flicker and eye strain to those sensitive to it.

 

Contrast Stability and Brightness

The brightness control gave us a good range of adjustment. At the top end the maximum luminance reached 357 cd/m² which nicely met the specified maximum brightness of 350 cd/m² from the manufacturer. Note that the 600 cd/m² spec you will see for peak luminance is only applicable when using the HDR feature and local dimming, which we will talk about more later on in the review. The typical normal SDR (Standard Dynamic Range) use brightness met the spec nicely.

There was a very good 335 cd/m² adjustment range in total, and so at the minimum setting you could reach down to a low luminance of 21 cd/m². This should be adequate for those wanting to work in darkened room conditions with low ambient light. A setting of 33 in the OSD menu should return you a luminance of around 120 cd/m² at default settings. It should be noted that the brightness regulation is controlled using Pulse Width Modulation for all brightness settings below 100% and so the screen may exhibit some flicker or cause some eye-care issues to some users. That was a shame.

    

We have plotted the luminance trend on the graph above. The screen behaves as it should in this regard, with a reduction in the luminance output of the screen controlled by the reduction in the OSD brightness setting. This is mostly a linear relationship as you can see between 100 and 10% brightness. From 10 - 0% there is a more gradual adjustment in the luminance output.

The average contrast ratio of the screen was good at 2026:1 but this left it a little shy of the specified 2400:1 minimum contrast ratio, and certainly less than the specified 3000:1 typical figure which was disappointing. 2026:1 is still very strong of course thanks to the VA panel, we had just hoped for slightly higher perhaps. We will see if calibration helps to improve this in a moment.

Testing Methodology

An important thing to consider for most users is how a screen will perform out of the box and with some basic manual adjustments. Since most users won't have access to hardware colorimeter tools, it is important to understand how the screen is going to perform in terms of colour accuracy for the average user.

We restored our graphics card to default settings and disabled any previously active ICC profiles and gamma corrections. The screen was tested at default factory settings using our new X-rite i1 Pro 2 Spectrophotometer combined with LaCie's Blue Eye Pro software suite. An X-rite i1 Display Pro colorimeter was also used to verify the black point and contrast ratio since the i1 Pro 2 spectrophotometer is less reliable at the darker end.

Targets for these tests are as follows:

• CIE Diagram - validates the colour space covered by the monitors backlighting in a 2D view, with the black triangle representing the displays gamut, and other reference colour spaces shown for comparison

• Gamma - we aim for 2.2 which is the default for computer monitors

• Colour temperature / white point - we aim for 6500k which is the temperature of daylight

• Luminance - we aim for 120 cd/m², which is the recommended luminance for LCD monitors in normal lighting conditions

• Black depth - we aim for as low as possible to maximise shadow detail and to offer us the best contrast ratio

• Contrast ratio - we aim for as high as possible. Any dynamic contrast ratio controls are turned off here if present

• dE average / maximum - as low as possible. If DeltaE >3, the color displayed is significantly different from the theoretical one, meaning that the difference will be perceptible to the viewer. If DeltaE <2, LaCie considers the calibration a success; there remains a slight difference, but it is barely undetectable. If DeltaE < 1, the color fidelity is excellent.

Default Performance and Setup

Above: Factory calibration report. Click for larger version

The C32HG70, despite being a gaming screen, comes with a factory calibration to try and ensure a reliable and accurate setup for most users. The screen is factory calibrated in the default 'custom' preset mode and comes with a specific calibration report for each individual screen as shown in our example above. From this report we can tell that the screen was factory calibrated to try and achieve a 6500k white point, 2.2 gamma and dE of less than 5.0.

Default settings of the screen were as follows:

Initially out of the box the screen was set with a high 100% brightness and so was overly bright and uncomfortable to use, so you will definitely need to turn that down. The colours looked bright and vivid and you could tell they were boosted a little compared with a standard sRGB screen we had set up next to it. The colours felt perhaps a little warm and contrast ratio seemed good thanks to the VA panel being used.

We went ahead and measured the default state with the i1 Pro 2. The CIE diagram on the left of the image confirms that the monitors colour gamut (black triangle) extends a fair amount beyond sRGB colour space (orange triangle), particularly in green shades. There is some minor over-coverage in blue shades, and a little more in reds but it's not quite a full wide gamut screen. Thanks to the Quantum Dot film, it's somewhere in-between. We measured using ChromaPure software a 127.0% sRGB gamut coverage so it was stretching a fair amount beyond the typical sRGB reference, as advertised. This measured colour space coverage corresponds to 93.6% of the DCI-P3 reference which meets the Ultra HD Premium defined spec for HDR content, and 67.2% of the Rec.2020 reference.

sRGB gamut coverage in default custom mode (left) vs sRGB preset color mode (right)

There is an sRGB mode available in the 'color' section of the OSD menu which restricts the colour space and bring it closer to the sRGB reference. You can see that comparison of the measured colour space in the CIE diagrams above, where the sRGB preset mode more closely matches the sRGB reference. This cuts down the slight oversaturation in greens and reds and might be useful if you are doing some more colour critical work and need to work more closely with sRGB content. In that mode we measured 104.9% sRGB coverage (77.3% of DCI-P3 and 55.5% Rec.2020) which is much nearer to sRGB than the default 127.0% sRGB coverage in the 'custom' mode. There are some OSD settings which are locked in this preset mode, but thankfully brightness is still available so you can set the screen to a comfortable brightness level. This at least makes this mode useable. Handy to have it available as an option for more precise sRGB emulation.

Default gamma (in both custom and sRGB modes) was recorded at 2.2 average, leaving it with a very small 1% deviance from the target which was good news. White point was measured at a slightly warm 6097k which left it 6% out from the 6500k we'd ideally want for desktop use. There are a range of other colour temp presets available in the menu along with a user configurable mode where you have access to the individual RGB channels for the calibration process.

Luminance was recorded at an extremely bright 376 cd/m² which is too high for prolonged general use, you will definitely need to turn that down. The screen was set at a default 100% brightness in the OSD menu but that is easy to change of course to reach a more comfortable setting without impacting any other aspect of the setup. The black depth was 0.18 cd/m² at this default maximum brightness setting, giving us a very good static contrast ratio of 2099:1 which was a little lower than the specified 2400:1 "minimum" figure from Samsung. Colour accuracy was moderate out of the box with an average dE of 3.2, but a max of 9.0 where blue shades seem to be an issue. Still on average within the factory calibration targets. Testing the screen with colour gradients showed smooth gradients with only minor gradation evident in darker tones. There was no sign of any colour banding which was good news.

All in all the factory calibration seemed to be pretty good. Gamma and dE targets were achieved, and white point was only a small 6% out from the target. We had a wider colour gamut as advertised, extending to 127% sRGB and the VA panel contrast ratio was high.

Calibration

We used the X-rite i1 Pro 2 Spectrophotometer combined with the LaCie Blue Eye Pro software package to achieve these results and reports. An X-rite i1 Display Pro colorimeter was used to validate the black depth and contrast ratios due to lower end limitations of the i1 Pro device.

We adjusted the RGB channels and brightness setting as shown in the table above as part of the guided calibration process. These OSD changes allowed us to obtain an optimal hardware starting point and setup before software level changes would be made at the graphics card level. We left the  LaCie software to calibrate to "max" brightness which would just retain the luminance of whatever brightness we'd set the screen to, and would not in any way try and alter the luminance at the graphics card level, which can reduce contrast ratio. These adjustments before profiling the screen would help preserve tonal values and limit banding issues. After this we let the software carry out the LUT adjustments and create an ICC profile.

Average gamma was maintained at 2.2 average and corrected the minor 1% deviance we'd seen out of the box. The white point had now been corrected to 6486k, which addressed the slightly warm 6% deviance we'd seen before. Luminance had been improved thanks to the adjustment to the brightness control and was now being measured at a far more comfortable 120 cd/m². This left us a black depth of 0.05 cd/m² and created a slightly stronger static contrast ratio (than default) of 2322:1, bringing us closer to the minimum advertised spec of 2400:1. Colour accuracy of the resulting profile was excellent, with dE average of 0.6 and maximum of 1.2. LaCie would consider colour fidelity to be very good. Testing the screen with various colour gradients showed mostly smooth transitions with only some minor gradation in darker tones. There was no added banding thankfully which can sometimes be caused by adjustments to the graphics card LUT from the profiling of the screen. You can use our settings and try our calibrated ICC profile if you wish, which are available in our ICC profile database. Keep in mind that results will vary from one screen to another and from one computer / graphics card to another.

Calibration Performance Comparisons

The comparisons made in this section try to give you a better view of how each screen performs, particularly out of the box which is what is going to matter to most consumers. When comparing the default factory settings for each monitor it is important to take into account several measurement areas - gamma, white point and colour accuracy. There's no point having a low dE colour accuracy figure if the gamma curve is way off for instance. A good factory calibration requires all 3 to be well set up. We have deliberately not included luminance in this comparison since this is normally far too high by default on every screen. However, that is very easily controlled through the brightness setting (on most screens) and should not impact the other areas being measured anyway. It is easy enough to obtain a suitable luminance for your working conditions and individual preferences, but a reliable factory setup in gamma, white point and colour accuracy is important and not as easy to change accurately without a calibration tool.

From these comparisons we can also compare the calibrated colour accuracy, black depth and contrast ratio. After a calibration the gamma, white point and luminance should all be at their desired targets.

Default setup of the screen out of the box was pretty decent thanks to the factory calibration. Gamma was accurate at 2.2 with only a very minor 1% deviance which was great news as that can be a tricky area to correct if you don't have a calibration device. White point was only a small amount off the 6500k target (6% deviance) and easy to correct with some basic RGB adjustments in the OSD menu. Contrast ratio was strong thanks to the VA panel, even better after calibration and close to the minimum contrast ratio spec from Samsung. You also have a useable and pretty good sRGB emulation mode if you need to tone down the colour gamut at all from the default Quantum-Dot extended 127% sRGB coverage.

The display was good when it came to static contrast ratio compared with most of the other models shown here. We measured a 2322:1 calibrated contrast ratio which was certainly a lot higher than you can achieve from an IPS or TN Film panel (about 1100:1 maximum from those technologies). However, at 2322:1 it did fall a bit short of the specified 3000:1 'typical' figure, although was basically in line with the 'minimum' contrast ratio spec provided. It left it a little behind some other VA panels we've tested such as the Acer Predator Z35 (2813:1) and the Eizo Foris FG2421 (4845:1). As a reminder, this is the static contrast ratio for SDR (Standard Dynamic Range) content, and higher contrast ratios will be possible when viewing HDR content thanks to the local dimming technology. More on that later.

Viewing Angles

Above: Viewing angles shown from front and side, and  from above and below. Click for larger image

Viewing angles of the screen were fairly typical for a VA technology panel although better than some other VA panels we've seen of late. The viewing angles here were quite similar to the Acer Predator Z271 which had a 27" sized curved Samsung SVA panel, but they were better than a 34" ultrawide SVA panel from Samsung that was used in the Philips 349X7FJEW. So it does seem that VA viewing angles can vary depending on panel size at the moment.

The image became more washed out as you viewed it from a wide angle horizontally, and certainly vertical shifts were even more noticeable with some yellowy colour tone shift evident. The viewing angles were not as good as you will get from an IPS-type panel, but they are better than you will see from TN Film matrices. Somewhere in the middle is VA.

Users should also be aware that the panel exhibits the off-centre contrast shift which is inherent to the VA pixel structure. When viewing a very dark grey font for example on a black background, the font disappears when viewed head on, but gets lighter as you move slightly to the side. This is an extreme case of course as this is a very dark grey tone we are testing with. Lighter greys and other colours will appear a little darker from head on than they will from a side angle, but you may well find you lose some detail as a result. This can be particularly problematic in dark images and where grey tone is important. It is this issue that has led to many graphics professionals and colour enthusiasts choosing IPS panels instead, and the manufacturers have been quick to incorporate this alternative panel technology in their screens. We would like to make a point that for many people this won't be an issue at all, and many may not even notice it. Remember, many people are perfectly happy with their TN Film panels and other VA based screens. Just something to be wary of if you are affected by this issue or are doing colour critical work.

Above: View of an all black screen from the side. Click for larger version

We captured a photo of an all-black image as viewed from a side angle as shown above. This can help exhibit any glow you might see on different panel technologies. Here we saw some pale glow in places along the top and bottom but this was more related to uniformity issues that we will look at it a moment. There was no purple glow like we have seen on some other Samsung SVA panels including the 34" ultrawide Philips 349X7FJEW recently. It was also much less than the obvious white glow you get from most IPS panels.

Panel Uniformity

We wanted to test here how uniform the brightness was across the screen, as well as identify any leakage from the backlight in dark lighting conditions. Measurements of the luminance were taken at 35 points across the panel on a pure white background. The measurements for luminance were taken using BasICColor's calibration software package, combined with an X-rite i1 Display Pro colorimeter with a central point on the screen calibrated to 120 cd/m². The below uniformity diagram shows the difference, as a percentage, between the measurement recorded at each point on the screen, as compared with the central reference point.

It is worth noting that panel uniformity can vary from one screen to another, and can depend on manufacturing lines, screen transport and other local factors. This is only a guide of the uniformity of the sample screen we have for review.

Uniformity of Luminance

Uniformity of the screen was pretty good, with only small areas of the screen extending beyond a 10% deviance threshold which we would consider decent. The left hand side of the screen seemed to be slightly brighter than the right, ranging up to 126 cd/m² maximum, but that is only about 5% deviance from the centrally calibrated point so nothing you would notice in practice. The upper and lower edges showed a slight drop off in luminance, down to 105 cd/m² minimum (-14% deviance). Around 86% of the screen was within a 10% deviance from the centrally calibrated point which was good.

Backlight Leakage

Above: All black screen in a darkened room. Click for larger version

We also tested the screen with an all black image and in a darkened room. A camera was used to capture the result. The camera showed there was some clouding in some parts of the screen along the top and bottom edges, particularly on the right hand half of the screen. It was noticeable in a couple of areas in particular but it was not too bad. It would be difficult to spot this during any normal uses really, unless you're viewing a lot of dark content. The VA panel helped produce nice deep blacks though in this test.

Note: if you want to test your own screen for backlight bleed and uniformity problems at any point you need to ensure you have suitable testing conditions. Set the monitor to a sensible day to day brightness level, preferably as close to 120 cd/m² as you can get it (our tests are once the screen is calibrated to this luminance). Don't just take a photo at the default brightness which is almost always far too high and not a realistic usage condition. You need to take the photo from about 1.5 - 2m back to avoid capturing viewing angle characteristics, especially on IPS-type panels where off-angle glow can come in to play easily. Photos should be taken in a darkened room at a shutter speed which captures what you see reliably and doesn't over-expose the image. A shutter speed of 1/8 second will probably be suitable for this.

General and Office Applications

The screen features a 2560 x 1440 resolution which is fairly common nowadays, but the difference here is that it is on a slightly larger screen size than normal. The C32HG70 is 31.5" in size, making it 4.5" larger diagonally than the typical 27" models featuring this resolution. The larger screen size is designed to provide more immersion for multimedia and games, giving a bigger screen to look at, especially useful if you want to view it from a little further back than a typical PC viewing position. So how does this 2560 x 1440 resolution look on this larger screen? Well, it looks fine. You will see slightly larger font sizes of course with the 0.272mm pixel pitch here and so for office work it doesn't look quite as sharp as on a 27" model. Some people may even prefer this slightly larger font though for more comfortable reading, and it's certainly not too big we didn't think for a screen this size. We saw no issues with text clarity on this screen, which some users had reported to us. Perhaps this was addressed via one of the firmware updates along the way, but we didn't see any problems with clarity.

We liked the curved format of the display actually for day to day office work. It just felt a bit more comfortable than a flat screen on a model this size, bringing the corners a bit nearer to you. You didn't really notice the curve in normal use but we liked the feel. Probably down to user taste, so if in doubt try and see one in person. It is funny switching back to a flat display afterwards which appears at first to curve away from you. You do quickly get used to the curved format of this model.

The light AG coating of the VA panel doesn't produce any graininess to the image like some aggressive AG solutions can and so white office backgrounds look clean and clear. The viewing angles of the VA panel technology were moderate, providing a fairly stable images from different angles, although not as good as you can get from competing IPS based displays. There is some contrast and colour tone shift from wider angles and the image starts to become washed out. It was better though than some other VA panels we have tested. The off-centre VA contrast shift may also be a problem for colour critical work and photo editing and you may want to consider an IPS equivalent instead if that is your primary usage. The viewing angles are fine though here for general day to day and office work.

The default setup of the screen was good and represented a decent setup for most users. You can make a few simple RGB adjustments to bring the white point more in line, but the rest of it was pleasing. Especially considering this is a gaming screen and those are often set up very differently. No super-low gamma settings here! The 2322:1 calibrated contrast ratio was strong and certainly a strength of the VA panel technology, although a little disappointing given the expectations of the 3000:1 'typical' specification listed. Nevertheless it certainly exceeded anything possible from competing IPS displays in this size.

The brightness range of the screen was also very good, with the ability to offer a luminance between 357 and 21 cd/m². This should mean the screen is perfectly useable in a wide variety of ambient light conditions, including darkened rooms. A setting of ~33 in the OSD brightness control should return you a luminance close to 120 cd/m² out of the box. However, one issue with this screen is that the brightness regulation is controlled through the use of the now infamous Pulse-Width Modulation (PWM), and so those who suffer from eye fatigue or headaches associated with flickering backlights may have some issues. It is odd that this technique was used, and we have flagged it to Samsung.

There was no audible noise from the screen, even if you listened very closely and when testing patterns which sometimes cause these issues to become noticeable. The screen also remains cool even during prolonged use.

There is a special 'Eye Saver' mode available via the OSD menu (and quick launch using the 'right' direction shown above) which is designed to offer an "optimum picture quality suitable for eye relaxation" according to the user manual. It is supposed to reduce the blue light output of the screen. In practice, we found this to be quite an odd setting. First of all when you enable the setting the brightness control is locked. The screen goes more yellowy and pale, and appears to be more washed out. With the brightness control disabled, the luminance output is measured at 83 cd/m² and for some reason this mode seems to be artificially lowering the digital white point. Blacks become more grey, and we measured black at only 1.03 cd/m² giving us an extremely low 81:1 contrast ratio. We're not really sure what this mode is trying to do, but it didn't seem to be very useful.

The screen offers 2x USB 3.0 ports which can be handy, including one with fast charging support. They are all located on the back of the display so are not easy-access really. There are no integrated speakers, but headphone output connection is provided along with mic in/mic out if you need them. There are no further extras like ambient light sensors or card readers which can be useful in office environments. Remember this is gamer-orientated screen anyway. There was a good, wide range of ergonomic adjustments available from the stand with the important tilt, height and swivel adjustments available. You can quite easily obtain a comfortable position for a wide variety of angles although tilt and height were stiff so you might not want to move it around too often. The VESA mounting support may also be useful to some people as well for more flexibility especially given the deep profile of the screen and stand.

Above: photo of text at 2560 x 1440 (top) and 1920 x 1080 (bottom)

The screen is designed to run at its native resolution of 2560 x 1440 and at a up to 144Hz maximum native refresh rate. However, if you want you are able to run the screen outside of this resolution. We tested the screen at a lower 1920 x 1080 resolution to see how the screen handles the interpolation of the resolution, while maintaining the same aspect ratio of 16:9. At native resolution the text was sharp and clear. When running at a the lower resolution the text becomes noticeably more blurry. You lose a lot of screen real-estate as well of course but if your system struggles with the higher refresh rates it might be an option for gaming. It's better to stick with the native resolution if you can though.

 

 
Responsiveness and Gaming

The C32HG70 is rated by Samsung as having a 1ms response time. This is quoted in a slightly different way to most of the monitor market as it is specifically a MPRT (Motion Picture Response Time) classification, which is a system used to try and articulate the responsiveness of a panel in the way it is perceived by the user, as opposed to looking at grey to grey (G2G) measurements or anything like that. Some manufacturers quote MPRT measurements, but also provide a comparative G2G figure, since that is used widely across the market at the moment. On this screen, there is no G2G figure, and the fact they are quoting 1ms MPRT relates to the use of a strobed backlight system - more on that in a moment.

Given this different way to quote a response time, it is a little unclear then whether overdrive / response time compensation (RTC) technology is being used to boost pixel transitions across grey to grey changes. Usually a G2G figure is a clear sign that overdrive is being used on the panel. Given this is a VA technology panel from Samsung, which can be quite slow if you don't apply overdrive to it, it is safe to assume there is an overdrive impulse applied here on the C32HG70 in some way.

There is a user control in the OSD menu labelled as 'Response time' but contrary to expectation this does not actually control the overdrive or affect pixel response times. There are 3 modes available - standard, faster, fastest. The faster and fastest modes actually enable a strobed backlight system to improve the motion clarity, giving rise to the 1ms MPRT spec being quoted. So there is actually no control over the overdrive and pixel response times, only control over a standard mode (strobing off) and two slightly different strobing modes. We will look at all of this in more detail in a moment but we are reliant here on the preset overdrive levels from Samsung.

The part being used is the Samsung LSM315DP01 SVA (VA-type) technology panel. We will first test the screen using our thorough response time testing method. This uses an oscilloscope and photosensor to measure the pixel response times across a series of different transitions, in the full range from 0 (black) to 255 (white). This will give us a realistic view of how the monitor performs in real life, as opposed to being reliant only on a manufacturers spec. We can work out the response times for changing between many different shades, calculate the maximum, minimum and average grey to grey (G2G) response times, and provide an evaluation of any overshoot present on the monitor.

We use an ETC M526 oscilloscope for these measurements along with a custom photosensor device. Have a read of our response time measurement article for a full explanation of the testing methodology and reported data.
 

Response Times

First of all we tested the screen in the 'standard' response time setting. This disables the strobed backlight system, allowing us to measure the actual pixel response times across a range of G2G transitions. We tested the screen in this 'standard' mode at a range of refresh rates from 60 to 144Hz, which all returned the same results from pixel response times as shown above.

As you can see, response times were somewhat mixed. Transitions from black to grey were particularly slow, a common issue with VA-type panels and something we've seen many times before and from most VA panels. For instance the change from black to dark grey (0 > 50) was measured at 37.5ms.

Pursuit camera tests demonstrating real perceived blurring levels. Note the dark trailing particularly on darker backgrounds due to slow rise times

In practice, this meant that you could see some issues with black smearing on moving content which you can see in our pursuit camera tests above. This was particularly problematic with darker backgrounds. Transitions from light to dark (fall times) were much better thankfully, with an average of 7.6ms G2G measured. It was the slow changes from dark to light (rise times) that were the issue here at 19ms average, dragging the overall combined response time average down to 13.3ms G2G.

0-50-0 transition example showing slow rise time. Horizontal scale 20ms

This gives rise to another problem, when it comes to refresh rate. This is a native 144Hz capable panel, but for high refresh rates to function correctly you need to have response times that can keep up with the frame rate demands. At 144Hz for instance, a new frame is being sent to the screen every 6.94ms (144 frames per second). The pixel response times need to be able to keep up with the frame rate or you will often see additional motion blurring and smearing. So here on the C32HG70 if we are generous and ignore the particularly slow transitions, the average G2G response time would be about 8.7ms. That is fast enough to support up to 100Hz just about, but anything higher than that will lead to added smearing and blurring. The response times are just not fast enough to keep up with the frame rates of anything above 100Hz. You would probably be best to limit your maximum refresh rate if you are using this 'standard' mode to 100Hz via the OSD menu option. We have fed this back to Samsung so perhaps it will be possible for them to make overdrive adjustments in future firmware versions.

 

Detailed Response Time Measurements

Having taken a small number of measurements above to test the response times at each refresh rate, we extended the range of transitions measured here. As a reminder there is actually no control over the response times themselves, and they remain the same in each of the three 'response time' modes in the OSD menu. The 'faster' and 'fastest' modes don't change the underlying pixel response times, they just enable the strobing backlight which we will talk about in more detail in a moment. The pixel response times also stay consistent at all refresh rates from 60Hz to 144Hz.

The average G2G response time was more accurately measured at 13.0ms which was quite slow overall to be honest. It is the rise times, the changes from dark to light shades, that cause the problem here and you can see that those response times are particularly slow. The changes from black to grey (0 > x) are around 20ms in most cases, with a change from black to dark grey (0 > 50) being even slower at 37.5ms. Those slow rise times are what leads to the black smearing on moving content that we talked about before, and demonstrated with our pursuit camera tests. We have seen this issue on many VA panels in the past, as those changes from black to grey often seem to be a problem with this technology it seems. You need a more aggressive overdrive impulse to boost them to faster speeds.

The rise times (16.7ms G2G average) drag the overall average response times down to the 13ms G2G figure. The fall times, changes from light to darker shades are much quicker with an average of 9.4ms G2G measured. With the overall response times being what they are, we felt that without the strobing backlight active (so in the 'standard' response time setting) you will probably want to limit your refresh rate to 100Hz maximum. That includes when using FreeSync to dynamically control the refresh rate range. There seemed to be some motion clarity improvements going from 60Hz to 100Hz thanks to the higher frame rate, but if you push the refresh rate above 100Hz you do start to get some additional blurring and smearing caused by the slow pixel response times. If you use the strobing backlight, that helps hide some of the blurring and smearing and so is more usable at 120Hz and 144Hz settings if you wish.

On a positive note, there is no overshoot at all on any transition so at least there was no added trailing or artefacts from an overly aggressive overdrive impulse. If anything, they can afford to turn the overdrive up to boost pixel response times here.

 

FreeSync 2

On this model, FreeSync is supported over the DisplayPort and both HDMI interfaces. The FreeSync modes need to be enabled via the OSD menu, but when you activate either of the modes offered, the response time setting is locked out and reverts to the 'standard' mode. This is because the 'faster' and 'fastest' modes are actually operating a strobed backlight, and that cannot function at the same time as a variable refresh rate unfortunately. So with FreeSync turned on, you are left with the response times and motion clarity issues we talked about earlier. There are some very slow transitions from black > grey shades which results in dark smearing in certain content. And because the response times are not fast enough across the board, they can only really handle a refresh rate up to 100Hz before additional frame rate related smearing and blurring starts to become an issue as well.

You will probably want to limit your FreeSync upper refresh rate to 100Hz we think which still offers improvements over common 60Hz screens, and is of course a lower demand then on your system and graphics card when trying to run at the full 2560 x 1440 resolution and maximum 144Hz refresh rate.

The FreeSync range of the screen varies depending on which FreeSync mode you select in the OSD menu, with two options available for 'Standard' and 'Ultimate'. The ranges listed in the table above are based on the current latest v1013.0 firmware and you can see that the ultimate mode gives you a much wider range in which to operate. This is the recommended option to use if you are going to use FreeSync, and actually the range of 50 - 100Hz over HDMI is probably preferable to account for the previously mentioned motion clarity considerations. The 'Standard' mode is designed to give a more limited range if for any reason you experience any issues with artefacts, flicker or any other oddities in the Ultimate mode. That might vary from system to system and from game to game, so it's there just as a fall back which is handy.

 

Strobed Backlight and Motion Clarity

A strobing backlight is used on a display to reduce the perceived motion blur in practice, helping to improve motion clarity and make it easier to track moving objects on an LCD screen. Have a read of our detailed article about motion blur reduction backlights for more information or if you're unfamiliar with these technologies and why they are used.

We tested the strobed backlight system on the C32HG70 to see what impact it has on motion clarity. On the CHG70 series this operates a little differently than we've seen on other screens in the past. The strobing is actually enabled when you switch up to the 'faster' or 'fastest' settings in the Response Time control. This doesn't change the pixel response times as the name might imply, but instead enables the blur reduction strobing backlight system. Underlying pixel response times remain unaffected, but you do see some improvements in perceived motion clarity.

Faster Setting

Strobing backlight cycling, 144Hz (scale = 5ms)

When you change to the 'Faster' response time mode the brightness setting is disabled, and the screen is actually set to its maximum brightness output. This avoids the PWM backlight dimming we know is active when you move the brightness control below 100%, to avoid any conflicts with the on/off strobing of the backlight here for motion benefits. This also helps provide a decent luminance since the strobing system results in a drop from the default maximum luminance. So when you enable the 'faster' mode, luminance drops from the maximum 357 cd/m2 we see in the 'standard' setting (where strobing backlight is off), down to 211 cd/m2. This is a good luminance for a strobed backlight system actually, surpassing many screens we've tested in the past which are often criticised for being too dark in these blur reduction modes. However, it is a shame that you cannot manually adjust the brightness down from there if you wanted to, but it's presumably a complication because of the PWM backlight dimming. You may need to alter brightness digitally through your graphics card or game setting if you need it to be lower, although that will crush the contrast ratio somewhat.

The strobing operates in sync with the 144Hz refresh rate as shown from the oscillograph above. The backlight is turned off once per frame, so at 144Hz that is every 6.94ms. This strobing in sync with the frame rate delivers optimal blur reduction benefits and avoids any issues with ghosting images or stutter that can appear if they are not in sync. We noticed that the strobing actually stays at 144Hz even if you change your refresh rate setting in Windows down to something lower. For example if you change your windows refresh rate to 100Hz, the strobing still operates at 144Hz. If you want to sync the strobing to a lower refresh rate this has to be done via the OSD menu on the monitor itself, using the additional 'Refresh Rate' setting. Here you can set the refresh rate of the monitor, and the strobing then syncs up to that. This works at the settings of 144Hz, 120Hz and 100Hz but if you switch to the 60Hz mode the strobing is not available. At 60Hz the 'faster' and 'fastest' response time settings are greyed out and not available, so you cannot use strobing at a 60Hz rate.

Fastest Setting

Strobing backlight cycling, 144Hz (scale = 5ms)

When you enable the 'fastest' response time setting there is a small change to the behaviour of the strobing. You can see a small second strobe is introduced per frame from the oscillograph. The strobing is still in sync with the refresh rate you set in the monitor OSD and we didn't notice much real change in practice to be honest. The maximum luminance was the same as the 'faster' mode, and there was minimal change to the perceived motion clarity. See our pursuit camera tests in a moment for more info. You may want to try both modes to see which one you prefer, but there didn't seem to be any significant difference.

 

Maximum Blur Reduction Brightness - Display Comparison

For ease of reference we have also provided a comparison table below of all the blur reduction enabled displays we've tested, showing their maximum luminance before blur reduction is turned on (normal mode) and their maximum luminance with the feature enabled. This will give you an idea of the maximum brightness you can expect from each model when using their blur reduction feature, if that is important to you. A lot of people want a brighter display for gaming and sometimes the relatively low maximum luminance from blur reduction modes is a limitation.

These comparisons are with the refresh rate as high as is available for the blur reduction feature to function. For most this is at 120Hz, but some also support the feature at higher. You can achieve a slightly brighter display if you use the feature at lower settings like 85 or 100Hz if available, since the strobes are less frequent, but it's not a significant amount. That can also introduce more visible flicker in some situations.

Note: Pulse Width setting at max where applicable.
*Note 2: The Acer XB270HU was later updated to include a 120Hz mode, which will produce a slightly darker maximum luminance
 

Pursuit Camera Tests - Motion Clarity

We've already tested above the actual pixel response times and other aspects of the screen's gaming performance. We wanted to carry out some pursuit camera tests as well to give an even more complete idea of the performance of this screen.

Pursuit cameras are used to capture motion blur as a user might experience it on a display. They are simply cameras which follow the on-screen motion and are extremely accurate at measuring motion blur, ghosting and overdrive artefacts of moving images. Since they simulate the eye tracking motion of moving eyes, they can be useful in giving an idea of how a moving image appears to the end user. It is the blurring caused by eye tracking on continuously-displayed refreshes (sample-and-hold) that we are keen to analyse with this new approach. This is not pixel persistence caused by response times; but a different cause of display motion blur which cannot be captured using static camera tests. Low response times do have a positive impact on motion blur, and higher refresh rates also help reduce blurring to a degree. It does not matter how low response times are, or how high refresh rates are, you will still see motion blur from LCD displays under normal operation to some extent and that is what this section is designed to measure. Further technologies specifically designed to reduce perceived motion blur are required to eliminate the blur seen on these type of sample-and-hold displays which we will also look at.

We used the Blurbusters.com Ghosting Motion Test which is designed to be used with pursuit camera setups. The pursuit camera method is explained at BlurBusters as well as covered in this research paper. We carried out the tests at 144Hz refresh rate, with and without Blur Reduction enabled. These UFO objects were moving horizontally at 960 pixels per second, at a frame rate matching refresh rate of the monitor.

 

We were very pleased with the results here as we had been on other blur reduction displays when the strobed backlight was enabled, with an obvious and marked improvement in perceived motion blur experienced. Tracking of moving objects became much easier and the image looked sharper and clearer when you used the 'Faster' and 'Fastest' modes which enabled the strobing. You can see from the pursuit camera tests the difference the strobed backlight makes - remember, these images are meant as a representation of what you would actually see with the eye. In the 'standard' mode where strobing was not active, you get a typical amount of motion blur, but the image becomes much sharper, clearer and easier to track once it is enabled.

One thing you will notice in particular on the dark background images is that there is some noticeable dark smearing behind the moving UFO. This is a result of those particularly slow pixel response times when changing from dark > light shades that we talked about earlier. This is a problem in all settings and is not eliminated sadly by the strobed backlight. It's a fairly common issue on VA panels to be honest. Maybe Samsung can improve the response times with a future firmware update if we are lucky.

We also used the BlurBusters full-screen TestUFO strobe crosstalk test as well to put the feature through its paces and were fairly pleased with the results. The upper half of the screen was clearer than the bottom, and in the bottom third of the screen some strobe cross-talk became pretty apparent. It is impossible to eliminate strobe cross-talk completely due to the way they operate, but the important thing is whereabouts on the screen this manifests itself and to what level. The central region (as pictured above) is probably the most important since that's where a lot of your gaming focus will be, where crosshairs and the likes are. We were pleased that there was only low levels of cross-talk here in the central region and the image looked good. The upper region was clearer still and perhaps the timing could have been altered slightly to move this clearer region down from the top to the centre perhaps? There was no option for the user to change the strobe timing which would have an impact on where this crosstalk appeared.

Gaming Comparisons

The above comparison table and graph shows you the lowest, average and highest G2G response time measurement for each screen we have tested with our oscilloscope system. There is also a colour coded mark next to each screen in the table to indicate the RTC overshoot error, as the response time figure alone doesn't tell the whole story.

These comparisons are based on the underlying pixel response times, ignoring any motion clarity benefits of strobing backlights etc. So on this screen the measurements were taken in the 'Standard' response time mode, while the active refresh rate had no impact on the measurements. With an average of 13ms G2G the screen was quite slow, lagging behind the other models listed here - most of which are gaming screens. Other competing VA technology screens like the AOC AGON AG352UCG for instance were a little faster at 10.2ms G2G average, and in fact had less of an overall problem with rise times and dark smearing than the C32HG70. The native higher refresh rate IPS models like the Asus ROG Swift PG279Q (5.0ms G2G) for instance had performed much better, and TN Film models like the Asus ROG Swift PG278Q (2.9ms G2G) could of course reach faster speeds and are specifically designed for gaming audiences.

Additional Gaming Features

• Aspect Ratio Control - the screen offers 8 options for aspect ratio control, available through the OSD menu in the 'game' section as shown. There are options for specific panel sizes (17" 4:3, 19" 4:3, 19" wide 16:10, 21.5" wide 16:9, 22" wide 16:10 and 23" wide 16:9), wide and auto. The Auto mode is handy as it will display the picture in the intended aspect ratio, while filling as much of the screen as possible. It would have been useful to include a 1:1 pixel mapping mode we felt for any unusual inputs, or if you don't want to interpolate the image to a larger size using the 'auto' mode. It was also missing a 5:4 aspect ratio mode option, despite the wide range of specific sizes listed which were all in 4:3, 16:10 or 16:9 aspect.
   

• Preset Modes - There are 4 gaming preset modes available in the menu. There are options for FPS, RTS, RPG and AOS modes. You can also set up 3 user configurable modes and save them if you want which is good. There's lots of flexibility here to set up specific modes for different gaming needs, with and without features like the strobed backlight and FreeSync modes on, depending on your requirements. Being able to quickly and easily switch between them using the additional 3 buttons on the bottom edge of the screen was handy.
   

• Black Equalizer - There is a setting available in the 'game' section of the OSD menu as pictured above which allows you to adjust the brightness of the dark areas of games. We've seen this kind of feature on other screens before and it can be handy where you are in a lot of dark environments to bring out some shadow detail. Although the higher static contrast ratio of the VA panel helps here too compared with other competing IPS and TN Film gaming screens.

Lag

We have written an in depth article about input lag and the various measurement techniques which are used to evaluate this aspect of a display. It's important to first of all understand the different methods available and also what this lag means to you as an end-user.

Input Lag vs. Display Lag vs. Signal Processing

To avoid confusion with different terminology we will refer to this section of our reviews as just "lag" from now on, as there are a few different aspects to consider, and different interpretations of the term "input lag". We will consider the following points here as much as possible. The overall "display lag" is the first, that being the delay between the image being shown on the TFT display and that being shown on a CRT. This is what many people will know as input lag and originally was the measure made to explain why the image is a little behind when using a CRT. The older stopwatch based methods were the common way to measure this in the past, but through advanced studies have been shown to be quite inaccurate. As a result, more advanced tools like SMTT provide a method to measure that delay between a TFT and CRT while removing the inaccuracies of older stopwatch methods.

In reality that lag / delay is caused by a combination of two things - the signal processing delay caused by the TFT electronics / scaler, and the response time of the pixels themselves. Most "input lag" measurements over the years have always been based on the overall display lag (signal processing + response time) and indeed the SMTT tool is based on this visual difference between a CRT and TFT and so measures the overall display lag. In practice the signal processing is the element which gives the feel of lag to the user, and the response time of course can impact blurring, and overall image quality in moving scenes. As people become more aware of lag as a possible issue, we are of course keen to try and understand the split between the two as much as possible to give a complete picture.

The signal processing element within that is quite hard to identify without extremely high end equipment and very complicated methods. In fact the studies by Thomas Thiemann which really kicked this whole thing off were based on equipment worth >100,1000 Euro, requiring extremely high bandwidths and very complicated methods to trigger the correct behaviour and accurately measure the signal processing on its own. Other techniques which are being used since are not conducted by Thomas (he is a freelance writer) or based on this equipment or technique, and may also be subject to other errors or inaccuracies based on our conversations with him since. It's very hard as a result to produce a technique which will measure just the signal processing on its own unfortunately. Many measurement techniques are also not explained and so it is important to try and get a picture from various sources if possible to make an informed judgement about a display overall.

For our tests we will continue to use the SMTT tool to measure the overall "display lag". From there we can use our oscilloscope system to measure the response time across a wide range of grey to grey (G2G) transitions as recorded in our response time tests. Since SMTT will not include the full response time within its measurements, after speaking with Thomas further about the situation we will subtract half of the average G2G response time from the total display lag. This should allow us to give a good estimation of how much of the overall lag is attributable to the signal processing element on its own.

Lag Classification

To help in this section we will also introduce a broader classification system for these results to help categorise each screen as one of the following levels:

• Class 1) Less than 6.94ms / 1 frame lag at 144Hz - should be fine for gamers, even at high levels

• Class 2) A lag of 6.94 - 13.88ms / One to two frames at 144Hz - moderate lag but should be fine for many gamers. Caution advised for serious gaming

• Class 3) A lag of more than 13.88ms / more than 2 frames at 144Hz - Some noticeable lag in daily usage, not suitable for high end gaming

For the full reviews of the models compared here and the dates they were written (and when screens were approximately released to the market), please see our full reviews index.

We have provided a comparison above against other models we have tested to give an indication between screens. The screens tested are split into two measurements which are based on our overall display lag tests (using SMTT) and half the average G2G response time, as measured by the oscilloscope. The response time is split from the overall display lag and shown on the graph as the green bar. From there, the signal processing (red bar) can be provided as a good estimation.

With Low Input lag mode turned off, the screen showed a total lag of 25.10ms as measured by SMTT. If we take out an element related to pixel response times (6.50ms) then we are left with an estimated signal processing lag of 18.6ms. This is just under 3 frames at 144Hz (or just under 2 frames if you limit to 100Hz) and represents a quite high level of lag.

Thankfully the screen also features a 'low input lag' mode in the OSD menu as shown above. This is available at all refresh rates except 60Hz (for some reason). At 60Hz, that option is greyed out, this includes when connecting external devices over HDMI. With low input lag mode turned on we saw an excellent improvement in the lag. The total display lag from SMTT measurements was now only 7.0ms, giving an estimated signal processing lag of only 0.5ms. This is basically nothing and makes the screen suitable for a wide range of gaming needs. A very good result there.

Movies and Video

The following summarises the screens performance in video applications:

• 31.5" screen size makes it a reasonable option for an all-in-one multimedia screen, but being quite a bit smaller than most modern LCD TV's of course.

• Curved screen format provides a level of immersion for movies and video, and is popular in the TV market as well right now.

• 16:9 aspect ratio is more well suited to videos, and is a better format than 16:10 or 4:3 aspect screens. Ultrawide 21:9 aspect ratio options would be more suitable though as they leave smaller borders on DVD's and wide screen content at the top and bottom.

• 2560 x 1440 resolution can support full 1080 HD resolution content but is not high enough to support Ultra HD 3840 x 2160 resolution natively without scaling it down.

• Digital interfaces support HDCP for any encrypted and protected content

• Good range of modern connectivity options provided with 1x DisplayPort 1.4 and 2x HDMI 2.0b offered.

• Cables provided in the box for DisplayPort and HDMI.

• Light AG coating providing clean and clear images, without the unwanted reflections of a glossy solution.

• Wide brightness range adjustment possible from the display, including a maximum luminance of ~357 cd/m² and a fairly decent minimum luminance of 21 cd/m². This should afford you good control for different lighting conditions. Brightness regulation is unfortunately controlled using PWM and so is not flicker free which may be an issue to some users.

• Black depth and contrast ratio are very good thanks to the VA panel at 2322:1 after calibration. Detail in darker scenes should not be lost as a result and blacks look deep. It was not as strong as some other VA panels though (nearer 3000:1 being fairly common), and not in line with the 3000:1 spec typical from Samsung which was a shame. It fell more in line with the 'minimum' spec.

• Extended colour space of around 127% sRGB thanks to the Quantum Dot coating, which can give a bit of a boost to colours making the screen appear a little more vivid. Not too oversaturated like using a wide gamut screen would be but it helped make the image a little more colourful we felt. This also allowed support for 93.6% of the DCI-P3 reference space needed for HDR support.

• There is a specific preset modes for 'cinema' on this model which made the image slightly cooler than our calibrated custom mode. Might be useful to set up for your movie viewing needs.

• Fairly decent pixel responsiveness which should be able to handle fast moving scenes in movies without much issue. You may see some dark smearing in some fast content where the pixel response times are not fast enough to keep up.

• Viewing angles are a little behind IPS screens and there is a more noticeable gamma and colour tone shift as you change your viewing position. The image becomes quite washed out. The viewing angles were better here though than we'd seen from some other VA panels which was good news and probably allows you to view the screen from different positions without too much trouble.

• A bit of backlight clouding was detected along the top and bottom edges but it was not too bad. You may pick this out sometimes when viewing movies where black borders are present in these areas.

• Good tilt and height adjustment range available from the stand making it pretty easy to re-position the screen for movie viewing from a distance, or with other people. They are quite stiff so you won't want to move it around too much, but thankfully the side to side swivel is easier and also handy for viewing from other positions.

• There are no integrated stereo speakers on this model but there is a headphone output connection if needed.

• Good range of hardware aspect ratio control options available including an 'auto' mode to handle any non- 16:9 formats.

• Picture in picture (PiP) and Picture By Picture (PbP) are not available on this model.
   

 

HDR (High Dynamic Range)

 

HDR stands for High Dynamic Range and is a technology just starting to make its way in to the desktop monitor market. It's been around in the TV market for a couple of years and is used primarily to provide a better dynamic range and contrast to the image for multimedia, movies and games - that being the difference between light and dark parts of an image. This improvement to the dynamic range is usually paired with other specific features under the banner term of "HDR" including a wider colour gamut for richer, more vivid colours and specs like a 10-bit colour depth support and a high Ultra HD resolution. Overall, an HDR Capable screen is designed to offer a more life-like images, with better contrast ratios between light and dark areas and more vivid, bright colours. You only need to go in to a high street store to observe the difference that HDR makes on TV sets, so we would encourage you to do that if you want to see first hand the improvements it makes to the image quality.

 

When you see the term HDR being used, especially in the monitor market where it is still in its infancy, you need to be aware that specs and performance will vary quite significantly. Our detailed HDR article talks a lot more about the various technologies used, including some standards which have been introduced to try and make HDR a little less of a free-for-all. We will try and provide a brief summary of some of the key HDR considerations and specs here in this review, while also looking at the HDR performance of this screen in more detail.

 

HDR Content Standards Support - HDR10

 

The C32HG70 is designed to support the HDR10 content standard, which is one of the two main standards in the industry today. Dolby Vision is the other key alternative and that is not supported on this screen as it does not carry the necessary Dolby Vision chip or certification, but HDR10 has been more widely adopted by the gaming hardware and software studios which has helped establish its position. This includes by Microsoft for the X Box One S and Sony for their PS4 and PS4 Pro consoles. How this content format war settles is likely to take some time, but the HDR10 standard seems to be the most likely to take hold in the monitor market for the time being.

 

Local Dimming Backlight - 8 Zone Edge Lit

 

On LCD displays, the static contrast ratio is still limited by the panel technology being used. So for a TN Film or IPS technology panel you are still limited by a contrast ratio of around 1000 - 1200:1, and on a VA type panel you might reach up to around 3000:1 or so. The quite well established Ultra HD Premium standards in the TV market for HDR dictate that you need a contrast ratio of >20,000:1 to conform to their specs. So how is this achieved from an LCD screen? The answer is local dimming, operating a little bit like Dynamic Contrast Ratios (DCR) of old. Rather than making the whole screen lighter or darker though depending on the displayed content, local dimming attempts to dim only the dark parts of a image, while making the light parts of the screen brighter. The result is a localised dynamic contrast which greatly improves the picture quality and dynamic range.

 

The effectiveness of this local dimming depends on how the backlight is operated. The most basic HDR capable screens might attempt this local dimming simply through edge-lit dimming where the panel is backlit by LED's along the sides of the screen and split into a number of zones. While you can do some level of dimming through the adjustment of the edge-lit LED's it gives limited control over the zones on a screen and its very tricky to pick out small areas effectively. A better approach to achieving accurate and reliable local dimming is to provide a backlight split in to hundreds of small zones behind the panel, where each zone is lit by a small set of LEDs. The higher the number of zones the better, as it gives more finite control over the image on the screen. Dark areas can be dimmed, while bright areas are accentuated and made brighter.

Representation of edge-lit local dimming zones on the C32HG70

 

On the C32HG70 the local dimming is achieved through an edge-lit backlight system. We were not able to officially confirm how many dimming zones were in use, but 8 seems to be a fairly typical for edge lit dimming and we expected that to be the number used here. In actual HDR tests it became apparent that the backlight was split in this way, and you could see individual zones light up as content changed. An indication of how the zones are split on the C32HG70 is provided above.

 

This will not give the same level of accuracy and control as a Full-Array-Local-Dimming (FALD) backlight where several hundred zones directly behind the panel can control the image in smaller areas. Even in those scenarios though you still need to keep in mind that the screen is not being individually lit at a pixel level, and so there is still some impact in varying the brightness of different zones. Depending on the content shown on the screen, you may seem some "blooming", where the bright areas have a halo or glow around them as zones bleed over in to one another. The smaller the bright point on the screen, the more tricky it is to correctly light it in an HDR environment without this blooming and haloing occurring. This blooming can become even more noticeable the larger the zones are, especially with edge-lit displays.

 

On the C32HG70 the limited number of zones meant that you got some blooming around bright points on the screen, as larger areas of the screen need to be controlled in one chunk. You could spot the individual zones changing broadly on moving content and certain HDR tests. It's hard to capture accurately to give you a visual representation here. It was not a massive issue or super-obvious, but you just need to be aware that controlling the screen through only a small number of zones has its limitations.

 

 

Ultra HD Premium Standard Conformity

 

Ultra HD Premium Spec Guidelines	Yes/no	Display Spec
At least Ultra HD Resolution 3840 x 2160		Quad HD 2560 x 1440 only
10-bit colour depth processing		8-bit + FRC panel
DCI-P3 colour space coverage		93.6% DCI-P3 measured
Suitable HDR connectivity		HDMI 2.0b and DisplayPort 1.4
at least 1000 cd/m2 peak luminance		623 peak cd/m2 measured
at least 20,000:1 active contrast ratio		20,767:1 maximum measured
Backlight dimming system (not defined in Ultra HD Premium requirements)	8 zone edge-lit local dimming

 

The C32HG70 does not conform fully to the Ultra HD Premium definitions but offers a pretty decent spec overall, meeting some of the requirements nonetheless. Firstly the Ultra HD resolution is not supported here, with only 2560 x 1440 being offered. That is a necessary sacrifice at the moment to allow support for the higher native refresh rates of 144Hz, and will not have any impact on the dynamic range or colours of the screen of course, only the resolution and sharpness. So the screen cannot truly display Ultra HD 3840 x 2160 resolution content without scaling it down.

 

10-bit colour depth support is provided thanks to the 8-bit + FRC panel, again conforming to the defined spec. From a PC you will need the relevant 10-bit workflow and graphics card to work with 10-bit content, but from other output devices the 10-bit support is there and ready to use - helping with colour range and gradation and supporting the extended colour space.

 

Speaking of colour space, the Quantum Dot coated panel allows for a high 93.6% (measured) coverage of the DCI-P3 reference space, giving a respectable coverage of this reference space, and certainly helping to provide vivid and bright colours in HDR content and multimedia. This is done without the need to use an expensive wide gamut LED backlight which can really add to the retail cost of the screen, as well as impact other areas like power consumption.

 

Connectivity wise the screen provides two different HDR compatible interface options. DisplayPort 1.4 for very modern and future graphics cards will support HDR from a PC - as long as you line up all the necessary components and software to achieve it. HDMI 2.0b will then also support HDR including from external games consoles and Blu-ray players.

 

The peak brightness of the display in HDR mode is rated at 600 cd/m² which is about 2 times as high as many displays in the market (when comparing their maximum brightness spec). This doesn't mean that the whole screen suddenly operates at 600 cd/m² which would be uncomfortably bright. The C32HG70 has a normal maximum brightness spec of 350 cd/m², but in HDR it can reach a 'peak brightness' of 600 cd/m². This is the brightness achieved where the lighter areas of the screen are increased during HDR content, producing a better active contrast ratio. Samsung tell us that the lower peak brightness (than 1000 cd/m²) was actually a preference here, since for close-up HDR PC gaming they felt that 1000 cd/m² would just be too bright. It might be ok for an LCD TV where you are viewing from a couple of metres away at least, but when you are as close to the screen as you are when using a PC the 600 cd/m² was more comfortable. We will test that performance in the next section.
 

 

HDR Luminance and Peak Brightness

 

In a new set of tests we measured the luminance and contrast performance of the screen in HDR mode in a variety of scenarios. A white box is displayed on the screen which covers 1% of the overall screen size initially. This is designed to show at several target luminance levels, starting at 100 and then changing to 400 and 1000 cd/m² (and beyond if needed). We measure the actual luminance of that white box to see how close to the target luminance the screen actually performs at each step. When the screen reaches the maximum peak luminance possible, we also measure the black depth of the screen at a point furthest away from the white area. This can then allow us to calculate the HDR active contrast ratio, the difference between the bright white area on screen, and the dark black areas elsewhere.

 

This 1% white screen coverage is designed to give a rough representation of how a small highlight area in HDR content might appear and work in normal multimedia. The box then increases to a larger size, covering 4, 9, 25, 49 and finally 100% of the screen area. This represents different sized areas of bright content in HDR multimedia. Again those progressively larger boxes are shown at the different luminance targets, and we measure the actual screen luminance achieved for each.

 

 

White window size	100 cd/m2 target	400 cd/m2 target	1000 cd/m2 target		Peak luminance (cd/m2)	Min black depth (cd/m2)	HDR contrast (x:1)
1%	96	390	623		623	0.03	20,767
4%	96	389	620		620	0.03	20,667
9%	96	387	619		619	0.03	20,633
25%	71	245	383		383	0.14	2,736
49%	62	232	363		363	0.16	2,269
100%	62	232	363		363	n/a	n/a

 

With the smallest 1% screen area white point as a starting point you can see that the luminance output of the screen was very close to the target at 100 and 400 cd/m². When the screen tries to show a 1000 cd/m² white box, we capture the peak luminance of the screen here since it is only capable of going up to around 600 cd/m² according to the product spec. In fact we measured a peak luminance on this display of 623 cd/m², achieved when there is only a small (1% in this example) bright area on an otherwise dark screen. With a peak luminance of 623 cd/m² we measured a black point on the same screen of only 0.03 cd/m². This gives rise to a HDR contrast ratio of 20,767:1. This is above the requirements for the Ultra HD Premium specifications as well and is very high. There is a large difference between the brightly lit white box, and the dark areas of the screen. We were pleased with the peak luminance and resulting HDR contrast ratio, living up to the spec nicely.

 

This performance is very similar then for some of the larger bright areas, including when the screen shows a 4% and 9% bright area. When the bright area gets larger still (25% coverage and above) the actual achieved luminance is under the target brightness levels. For instance at 25% coverage, the 400 cd/m² target box actually has a luminance of only 245 cd/m². Peak brightness is also lower at 383 cd/m², and the blacks are not quite a deep either at 0.14 cd/m². This gives a contrast ratio of 2736:1 which is still high, but obviously much lower. When there is a larger bright area on the screen the backlight has trouble meeting the desired luminance output it seems. The edge-lit local dimming has a harder time making the white parts brighter, and making the black parts darker at the same time. With only 8 zones in action, there is also some "blooming" where the backlight that is boosting the white area bleeds over a little in to the black regions as well. This is unavoidable on any zonal local dimming system, especially so with only 8 edge-lit zones. The black areas are not quite as deep as they could be since the blooming is causing them to be lighter.

 

 

HDR Settings and Operation

 

 

The screen will automatically detect if you are sending HDR content to it, and will display a small HDR label in the information tab of the OSD menu to confirm. You need to enable the 'local dimming' option (to either auto or on) for the HDR to function correctly, via the 'system' section as shown above. This local dimming is not available when you are using the 'faster' or 'fastest' response time modes which is what controls the strobing backlight, so you are not able to play HDR content while also using that system.

 

 

Using HDR Complexities
 

We will repeat what we said in our recent Dell UP2718Q review here as it's an important consideration you need to make. We should touch on the complexities of using HDR at this stage though, especially from a PC. It's actually quite complicated to achieve an HDR output at the moment from a PC and something you should be aware of before jumping straight in to a modern HDR screen.

 

You will need to ensure you have a compatible Operating System for a start. The latest Windows 10 versions for instance will support HDR, but from many systems you will see some odd behaviour from your monitor when it is connected. The image looks dull and washed out as a result of the OS forcing HDR on for everything. HDR content should work fine (if you can achieve it - more in a moment!) and provide a lovely experience with the high dynamic range and rich colours as intended. However normal every day use looks wrong with the HDR option turned on. Windows imposes a brightness limit of 100 cd/m² on the screen so that bright content like a Word Document or Excel file doesn't blind you with the full 1000 cd/m² capability of the backlight. That has a direct impact on how the eye perceives the colours, reducing how vivid and rich they would normally look. It also attempts to map the common sRGB content to the wider gamut colour space of the screen causing some further issues. Sadly Windows isn't capable at the moment of turning HDR on/off when it detects HDR content, so for now it's probably a case of needing to toggle the option in the settings section (settings > display > HDR and Advanced Color > off/on). Windows does seem to behave better when using HDMI connectivity so you may have more luck connecting over that video interface, where it seems to switch correctly between SDR and HDR content and hopefully negate the need to switch HDR on and off in the Windows setting when you want to use different content. This is not any fault of the display, and perhaps as HDR settles a bit more we will have better OS support emerge.

 

That is a little fiddly in itself, but a current OS software limitation. The other complexity of HDR content from a PC is graphics card support. The latest NVIDIA and AMD cards will support HDR output and even offer the appropriate DisplayPort 1.4 or HDMI 2.0a+ outputs you need. This will require you to purchase a top end graphics card if you want the full HDR experience, and there are some added complexities around streaming video content and protection which you might want to read up on further. There are graphics cards now available to provide that HDR option from a PC, but they are going to be expensive right now.

 

Finally, content support is another complex consideration from a PC. HDR movies and video including those offered by streaming services like Netflix, Amazon Prime and YouTube currently won't work properly from a PC due to complicated protection issues. They are designed to offer HDR content via their relevant apps direct from an HDR TV where the self-contained nature of the hardware makes this easier. So a lot of the HDR content provided by these streaming services is difficult or impossible to view from a PC at the moment. Plugging in an external Ultra HD Blu-ray player with HDR support is thankfully simpler as you are removing all the complexities of software and hardware there, as the HDR feature is part of the overall device and solution.

 

PC HDR gaming is a little simpler, if you can find a title which supports HDR properly! There are not many HDR PC games around yet, and even those that support HDR in the console market will not always have a PC HDR equivalent. Obviously more will come in time, but it's a little limited at the time of writing.

The other area to consider here is console HDR gaming. Thankfully that part of the gaming market is a bit more mature, and it's far simpler to achieve HDR thanks to the enclosed nature of the system - no software, graphics card or OS limitations to worry about here. If you have a console which can output HDR for gaming such as the PS4, PS4 Pro or X Box One S then the monitor will support those over the HDMI 2.0a connection. The screen conforms in part to Ultra HD Premium HDR specs as we've already mentioned and while it won't fully support 3840 x 2160 Ultra HD resolution or the full 1000 cd/m² peak brightness defined by the UltraHD Premium standards it does offer the necessary DCI-P3 colour space coverage, 10-bit input support and relevant connectivity options. Remember that for consoles you are limited to 60Hz refresh rate so actually options like the low input lag and strobing backlight will not be available here sadly.

 

None of these complexities are the fault of the display, and we should make it clear that the C32HG70 is certainly capable in itself of some degree of HDR content support, and will be HDR-ready for you in the future. You just need to be aware of the difficulties in actually getting HDR working from the PC side of things right now and understand that it might limit your uptake of HDR material as a consumer at the moment. The TV market is a simpler space for HDR right now, but although HDR is now emerging in the monitor market, the driving PC content side of things still needs time to catch up and settle.

Conclusion

The C32HG70 provided a really wide range of functions, options and extras to test and a really nice set of features for gaming audiences. You had modern connectivity from HDMI 2.0b and DisplayPort 1.4, loads of gaming preset modes in the OSD menu, user-customisable modes, black equalizer, good aspect ratio control, a strobed backlight, FreeSync support, 144Hz maximum refresh rate, low input lag mode. The list goes on...

Obviously the screen is aimed at gamers and on the most part it performs very well. There are some limitations in places so it's not the complete package. The strobing backlight works very well, giving decent improvements in motion clarity as you would hope for and a high luminance as well to avoid overly dark gaming like some competing screens will produce. It was a shame you could not alter the brightness a bit if you wanted to. Combined with the high native 144Hz refresh rate, the FreeSync support is very useful for those who have perhaps less powerful systems and will experience fluctuating frame rates, especially at the lower end. While not offering a full Ultra HD resolution, the bump from a common 1080p resolution to 1440p here is definitely welcome for not just gaming, but more general uses as well. Low input lag mode works really well and eliminates pretty much all the lag, although it's a bit of a shame you couldn't use it at 60Hz. We're not sure why. HDR gaming is supported and the screen does offer a pretty decent HDR spec. No, it doesn't quite meet the 1000 cd/m2 peak brightness, and the lack of Ultra HD resolution can be forgiven, but it does well in other areas. The Quantum Dot coating helps boost the colour space nicely and provides a more vivid appearance to improve your image. The 8-zone local dimming backlight is useful, producing peak brightness as advertised, and high active HDR contrast ratios. Implementing a full-array local dimming backlight is expensive (and difficult) so this was a reasonable moderate HDR support for a more general, and lower-cost gaming screen.

The main issue from a gaming point of view though was the response times. VA panels often have problems here, but the slow rise times caused some issues. This led to black smearing on moving content, particularly on darker backgrounds which you can't eliminate. The slow overall response times also created a limitation with the refresh rate, making it less than optimal to use the screen above about 100Hz. We hope that maybe Samsung can tweak the overdrive control with a future firmware revision if possible as that would really help in our opinion.

In non-gaming areas the other main draw-back of the screen was the use of PWM for backlight dimming. This could put some users off if they are susceptible to flicker or eye related issues. We were however pleased with the pretty decent factory calibration, something you don't really expect from a gaming screen. The contrast ratio was strong as you would hope from a VA panel too and we were pleased with the wider colour gamut, while still offering an sRGB emulation if you wanted. There was a good range of extra features and while the stand did offer good adjustments, we found it a bit restrictive as it was very deep.

The CHG70 models are an interesting new range, and it's nice to see Samsung back in the gaming market with new screens. If those response times could be improved somehow, that would make a big difference overall to the screen but it still offers a nice all round performance and some impressive features to be worthy of your consideration.

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