Towards the end of 2022 we saw a flurry of monitors released to market with Mini LED backlights, designed to offer significant improvements in HDR performance compared with the vast majority of so-called HDR monitors available. Best of all, many of these new models have been far more modestly priced than the top-end models available on the market, and compared with the early FALD (Full Array Local Dimming) and Mini LED monitors released. This makes them more accessible to a wider audience and at more reasonable price points. More people can now benefit from the advantages and performance of these Mini LED backlights without the screens being reserved for the super top-end.
We’ve already reviewed recently a 27″ 4K model from Cooler Master (GP27U), a 27″ 1440p resolution model (GP27Q) also from Cooler Master, and a 34″ ultrawide offering from AOC (AG344UXM) with Mini LED backlights. These higher end backlights allow for vastly improved local dimming of the backlight across the screen for HDR content which helps offer bright highlights above 1000 nits, as well as the ability to dim dark areas where needed, significantly improving the black depth and contrast ratio.
We have with us now a new monitor from Chinese brand KTC who are a manufacturer for displays from big-name brands like NEC, Samsung and ViewSonic and who are now building their own brand outside of China and in to markets in the US, Europe and the UK. If you want some background about who KTC are and a useful round-up of their monitor range, check out our article here. We’ve already reviewed recently their largest monitor, the 42″ sized OLED G42P5. This time we are reviewing their 27″ sized M27P20 Pro monitor. This model offers a 3840 x 2160 “4K” resolution, 160Hz refresh rate and a 576-zone Mini LED backlight. It uses the same panel as the Cooler Master Tempest GP27U, has a near-identical design (apart from the stand) and even has a very similar OSD menu software. There will be differences in setup, features and performance though so it will be interesting to see how the two compare.
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Key Specs and Features
- 27″ Fast IPS panel from AU Optronics (M270QAN07.0 – flat format)
- 3840 x 2160 “4K” resolution (16:9 aspect ratio)
- 160Hz max refresh rate (144Hz max for VRR)
- Adaptive-sync VRR for NVIDIA and AMD systems
- 576-zone local dimming Mini LED backlight
- >1000 nits peak brightness for HDR and VESA DisplayHDR 1000 certification
- 98% DCI-P3 wide colour gamut (118% relative coverage)
- 10-bit colour depth
- 1x DisplayPort 1.4, 1x USB type-C (DP alt mode and 90W power delivery) and 2x HDMI 2.1 video connections
- KVM function supported
- 2x USB ports, 2x 2W integrated speakers and headphone jack
- Stand with tilt, height, swivel and rotate adjustments
- Rear cover RGB lighting
Design and Features
The M27P20 Pro comes in a mostly matte black finish. It has a 3 side borderless panel with a total black edge of 9mm along the sides and top, and a thicker ~17mm black bezel along the bottom edge. The design from the front is minimalist and simple.
The base of the stand has an angular shape, recently updated from a more square design in fact that our sample had. The angled based is the new version provided with the screen. There is a cable tidy hole in the stand as you can see above, with a red trim section.
The back of the screen is encased in a matte black plastic. There is an RGB lighting ring around where the stand attaches to the panel, as well as two “wing” sections at the top. These can be customised somewhat within the OSD menu or turned off if you’d rather. These are not bright enough to cast a light on your wall behind the screen really, so are only really useful if you can see the rear of the screen in certain situations.
The stand provides a full range of ergonomic adjustments with tilt, height, swivel and rotate functions. All of these are smooth in movement and generally easy to use, although the tilt adjustment is quite stiff to operate. There’s a very good range of adjustments available from the stand though. The panel remains stable with very little wobble on the stand as you move it around or use the OSD buttons.
Connections are shown in the photo above on the back underside of the screen where there are 1x DisplayPort 1.4, 2x HDMI 2.1 and USB type-C (with DP Alt mode, data and 90W power delivery) available. There are also 2x USB data ports, a USB upstream port and a headphone jack provided. It might have been nice to have the USB ports and headphone jack in a more easy to get to position for easy access.
The OSD is controlled through a single joystick on the back right hand side of the screen (when viewed from the front). Navigation is generally quick and intuitive, although you have to select and enable settings sometimes by pressing ‘right’ on the joystick, when a press of the button seems to feel more logical. There’s a decent range of options to play with in here too.
One annoyance with the menu software is that quite a few settings trigger a warning about increasing/changing power consumption, and that happens every time. The most common of these is if you want to change the brightness setting, although once you’ve found the mode you like, you shouldn’t need to change it much. We had commented on a similar annoyance with the Cooler Master GP27U when we reviewed it, but the activation of this warning message is much less common and less intrusive on the M27P20 Pro thankfully. Still, it would be nice if you could turn off these warning messages.
The M27P20 Pro offers a wide colour gamut thanks to the use of a Quantum Dot coating which provides vivid and saturated colours well suited to a lot of gaming and to modern multimedia and HDR content. HDR is a key target use for this model given its high end Mini LED local dimming backlight. If you like the more colourful appearance then the screen does nicely here with a wide colour space. However, for a lot of normal desktop uses actually you want to work with a smaller SDR / sRGB colour space and that can be more difficult on a wide gamut screen. We will see how this screen handles that usage scenario shortly.
We first want to measure the accuracy of the default out-of-the-box setup relative to typical sRGB content, while also examining the screen’s suitability and accuracy for common wider colour gamut spaces such as DCI-P3, or for Adobe RGB which is used in the professional and photography markets quite often.
Note that we left the local dimming function disabled for these tests.
The screen is very bright out of the box being set at 90% brightness level and delivering a 432 cd/m2 luminance. That will need turning down. In this mode we measured a maximum brightness potential at 100% of 499.7 cd/m2, and a minimum of 47.2 cd/m2 at 0%, providing a nice wide range of adjustments to meet your requirements.
You can tell the screen has an especially wide colour gamut as the colours look very vivid and saturated. Our measurements show that the gamma curve is very good, being very close to 2.2 across the greyscale. The white point is a little too cool by 5% at 6846K, but nothing major although the balance of blue and green channels is quite a way off and will need correcting ideally for any colour critical work. The screen comes out of the box set to the ‘Normal’ colour temp mode but there are some others available for calibration which we will check out later. Because of the RGB balance we don’t have a great greyscale accuracy in this mode with an average dE of 5.7. Contrast ratio was mediocre for an IPS-type panel in this default mode at 846:1. We might be able to improve that through manual adjustments in our calibration section later.
From a colour point of view we have measured the screen’s native mode relative to the common sRGB colour space at the top, and then also relative to Adobe RGB at the bottom, a wider gamut colour space often used in the photography and professional market. Thanks to the Quantum Dot screen coating there is a very wide 149.1% relative coverage of sRGB, with large over-extension of this reference space in red and green shades particularly, making them look very saturated in practice. When viewing sRGB/SDR content in this default mode, colour accuracy is bad at dE 6.0 average but that’s common on wide gamut screens because of the over-coverage of the colour space. We will test sRGB emulation options in a moment for more accurate work with standard gamut content.
The bottom section shows that there is good coverage of wider colour gamut spaces like DCI-P3 (98.3% absolute) and Adobe RGB (96.9% absolute), although both also over-extend in this native gamut mode by a considerable way (118.8% and 127.8% relative coverage respectively). Although this does mean that in theory you can work with those wider gamut spaces nicely, if you have a way to clamp the colour space back to the intended area either from the monitor itself (tested in a moment), or via calibration and profiling at a software level. With the large over-coverage even of the Adobe RGB space, we had poor colour accuracy in this default full gamut mode for those colours, with dE 4.2 average. This is all to be expected really from a screen with such a wide colour gamut, but it will be interesting to see how we can tame this via the other monitor modes.
The M27P20 Pro provides an sRGB emulation mode in the OSD that can allow you to restrict the colour gamut back to the more common sRGB / SDR reference space. It’s available via the ‘Display’ part of the menu under the ‘Professional modes’ option. These modes can be useful if you want to avoid the over-saturation in the native wide gamut mode or specifically work with and view SDR content, although it’s also possible to use other methods such as graphics card clamping, or carry out calibration and create ICC profiles. Having a usable and working sRGB emulation mode from the monitor itself is the easiest method though, and can be used for all different applications, inputs and modes if it is well set up.
The sRGB mode is unfortunately locked in many OSD settings, including the whole colour section of the menu. You do thankfully have access to the brightness control to adjust the screen as you like, and move away from the very bright default setup of 466 cd/m2. However, we are now at the mercy of KTC’s factory calibration in terms of gamma and colour setup. The gamma is good on the whole, although it is a bit low in the darkest grey shades which can lead to a loss in shadow detail in darker shades. The white point and greyscale are both too cool, and you can see the blue channel is not balanced with red and green in the graph. We had a 7% deviance for the white point at 6962K. Not terrible, but a bit cooler than our preferred target of 6500K. Without access to the colour settings this will be hard to correct unless you have a calibration device. Contrast remained similar to the out of the box setup, at 854:1 which is moderate for an IPS-type panel.
Clamping of the very wide native gamut of the screen (~149% sRGB relative coverage in native mode) back to the defined sRGB space was good, although it went slightly too far, and we now had a 92.2% absolute coverage now. Basically all the over-coverage had been eliminated though, but we’d gone a bit too far and left the screen slightly short in the red shades. Colours now looked more muted of course than in the full wide gamut mode, but they are far more accurate for sRGB and SDR content. We measured a 2.5 dE average which was much better and represented an overall reasonable colour accuracy for this mode. With access to brightness still available to the user, this is a usable sRGB emulation mode on the whole.
Adobe RGB emulation
The M27P20 Pro also includes a mode for the Adobe RGB colour space, useful in the professional and photography markets.
This mode had decent overall tracking of the 2.2 gamma although it was a bit high in lighter grey shades which can lead to some washing out of bright details. In this mode the white point and colour temperature were warmer than our target, with a 10% deviance for the white point measured at 5872K. The sRGB mode had been a bit too cool, now this was a bit too warm. You can see the red channel balanced poorly with the other blue and green channels in the graph. We did have a slightly better contrast ratio in this mode at 911:1 though. Like the sRGB mode, the brightness control was available so you can adjust the overly bright 481 cd/m2 thankfully, but also like the sRGB mode you have no access to the colour settings at all, so it’s not easy to correct the white point or colour temp.
Clamping of the colour space was again a bit too aggressive in this mode. On the one hand, it’s certainly cut back on the large over-coverage of the native mode (127.8% relative coverage), especially in red and blue shades where the monitors native gamut goes a long way beyond the Adobe RGB space. But then it goes a bit too far, and now we have some under-coverage of red shade instead, resulting in a 93.0% coverage of the colour space. Still, by emulating the Adobe RGB space quite well, we definitely had a better colour accuracy that we would rate as reasonable, with dE average of 2.5. This is far better than the default colour space which had a 4.2 dE average for Adobe RGB colours.
This is a usable mode as well if you wanted to work specifically with Adobe RGB content for photography or professional applications, and can live with a warmer default image and not-quite-perfect colour space. If you have a calibration device you would be better profiling the native gamut mode back to Adobe RGB and using the ICC profile in colour aware applications for more accurate Adobe RGB colour space clamping and correction of the colour temperature too.
The M27P20 Pro also includes a mode for the DCI-P3 colour space, applicable in the HDR content creation and multimedia markets.
This mode has a very accurate gamma curve overall which is great news. It is also the closest mode to our 6500K white point with a small 4% deviance at 6263K. Contrast ratio remained basically as it had before at 873:1. You still have access to the brightness control, but none of the colour settings, the same as in the sRGB and Adobe RGB modes.
Like the Adobe RGB mode again, this DCI-P3 mode did cut down on the very large native gamut nicely, but went slightly too far in red shades, resulting in a 93.3% coverage of DCI-P3. The colour accuracy was good overall in this mode, and again we would say this is a decent usable mode generally if you need to work in this colour space, and tame somewhat the very wide default gamut. Having a calibration device would give you better control over the colour space profiling if needed.
Note that the calibration here is with local dimming turned off
Calibration and profiling can produce very good results if you have a suitable calibration device and software. This was profiled to 2.2 gamma, 6500k colour temp and to the sRGB colour space. The screen was left in its native wide gamut mode, but this profile will be used in colour-aware applications (e.g. Photoshop) to map back to sRGB in this instance. You can see the recommended OSD settings above that go along with this profile. The only challenge here seemed to be correcting the red colours for some reason, showing a dE up to 3.7. Everything else was corrected very nicely. Our calibrated ICC profile for this display is available now for our Patreon supporters and will be added to our main database in the coming months.
SDR Local Dimming
KTC provide the option to enable the local dimming backlight even in SDR mode, which could potentially be useful for gaming and multimedia. We wouldn’t really recommend using it for general uses, photography, professional applications etc as it could impact your accuracy, but it can give you a nice contrast and visual boost for dynamic content. It can offer impressive increases to contrast in those situations as the backlight can be turned right down to produce much deeper blacks.
When you enable local dimming in SDR mode you do not get an increased peak brightness compared to SDR mode though (like you did on the Cooler Master Tempest GP27U), but the maximum brightness capability of the screen is still very good as covered below and more than enough for SDR content. This is preferable operation though for SDR local dimming, as you don’t want the screen going massively brighter when the tone mapping is not there like it is for HDR, it just makes it very difficult to use. Here, you can just leave the screen brightness at a comfortable setting, and instead benefit from the local dimming improving the black depth, and therefore contrast ratio. This works very well.
For these tests we would normally switch to the sRGB gamut mode, as SDR content is based on that colour space and it would provide more accurate colours as as result. However, with nearly all the OSD settings being locked in the sRGB mode, this created a problem as enabling the local dimming setting skews the gamma curve massively. We measured an average gamma of 3.3 in fact in the sRGB mode, with no option to switch to any other gamma setting in the OSD menu to try and bring it closer to our 2.2 target while in that emulation mode.
Instead we need to use the ‘Native’ wide gamut mode which you may be ok with for your SDR gaming and multimedia if you are happy with the colours being more saturated (and unrealistic) and vivid. However, this won’t be as accurate for SDR content which should be rendered in the sRGB colour space really. It’s a shame that you can’t use the monitor’s sRGB emulation mode and still have access to the gamma controls, so that you can get a better setup for SDR local dimming.
Anyway, we first of all tested the brightness range and improved contrast with local dimming enabled in each of the two modes available in the menu. We used a 10% APL for this test:
|Local Dimming Setting OSD setting||Max 100% (nits)||Min 0% (nits)||Local contrast||Max full screen contrast|
The brightness levels possible are basically the same with local dimming enabled and disabled when in SDR mode as we said above. Set the screen to a comfortable brightness for your content. There are decent improvements in the contrast ratio though now that dark areas can be dimmed more effectively by the Mini LED backlight. The local contrast (between adjacent light and dark areas) was improved a modest amount to ~2500:1, a decent step up from the screens native ~846:1 in the Native mode with local dimming turned off. Max screen contrast (areas measured far apart from one another) was impressive at >50,000:1. This shows how much the Mini LED backlight can improve the contrast ratio in real use, even in SDR content in this example.
We also measured the setup in the Native mode but with the local dimming enabled. We adjusted that to get a ~120 nits luminance but feel free to use whatever you like for your content.
After a lot of experimentation, the main change we needed to make with local dimming enabled in SDR content was to the gamma setting. We moved this down to the lowest available setting of 1.8 in the OSD menu which still left us with a high gamma of 2.5 average. Closer to our target 2.2 certainly than leaving the screen set to its own 2.2 mode, but still very high. With our adjusted settings from earlier on in the review when we calibrated the screen we did have a decent white point and colour temp. The main benefit of course with enabling local dimming is the significantly improved contrast ratio and black depth.
Colour accuracy remains a challenge when using the screens native mode if you’re viewing sRGB/SDR content, as the wide colour gamut leads to over-saturated colours and high dE. For gaming and multimedia this might not be a massive problem though and may even be preferred by some people. It’s a shame that if you wanted to restrict the screen to the sRGB colour space through it’s provided emulation mode, you lose access to the gamma setting and so cannot get that any closer to a sensible level via the screen. Only the ‘Native’ gamut user mode allows you access to the gamma setting in the menu, so is really the only realistic option to use if you want to enable local dimming for SDR. Unless KTC release a firmware update later on which allows you access to the gamma and colour settings in the emulation modes.
General and Office
The M27P20 Pro features a 3840 x 2160 Ultra HD resolution (“4K”), all packed in to a 27″ sized screen. The higher resolution is not about providing more screen real-estate here, it’s about providing a sharper and crisper image, while still operating with a similar desktop area and same font size to the 1440p models. It is providing a higher pixel density (Pixels Per Inch, PPI) to improve the definition and sharpness of the image. Whether or not you will benefit from this depends on several factors including viewing distance and visual acuity. You need to us operating system scaling to handle this higher resolution properly though. If you try and run the screen without any scaling at 3840 x 2160 the 0.156mm pixel pitch makes everything far too small and tiny. On this 27″ model, if you increase the scaling to 150% for comfortable text size, you actually end up with the same workspace area as 2560 x 1440, but at a much higher PPI pixel density – and therefore a potentially sharper image for some people. For those wanting a high pixel density for CAD, design, photo work etc, this is an attractive option. Of course it’s also great for providing a sharp and crisp image for gaming and multimedia. The image was very sharp and crisp and text was very clear. It is a little debatable whether you will gain much benefit from the higher PPI on a screen this size compared with a 2560 x 1440 standard model, but some may notice picture quality and sharpness improvements.
Keep in mind that not all Operating Systems and applications handle scaling the same. More recent versions of Windows tend to handle it all better, and recent versions of Mac OS are pretty solid as well. Some applications and games don’t handle scaling correctly and so you can end up with some things with very minute text and fonts and some things which don’t scale completely in every place. Keep this in mind if you’re selecting any super high resolution display as it could be an important factor. You need to ensure you have the necessary operating system and applications to handle scaling effectively for your needs. It does make life a bit more complicated than if you just ran at a native resolution, which is where the more common 2560 x 1440 res fits in to the 27″ display space. If you have the necessary software and operating system then the 4K resolution provides a very sharp and crisp image on a screen this size.
The IPS panel used for this screen offers some solid all round performance including wide viewing angles and a stable image quality that you’d expect from this technology. You get a typical pale glow on dark content when viewed from an angle though. The contrast ratio is reasonable for an IPS-type panel at around 895:1 after calibration, but not as good as VA panels or next generation “IPS Black” panels. The backlight adjustment range (47 – 500 cd/m2) is very good, including adjustment for darker room conditions.
We confirmed that when the local dimming function is turned off, the backlight operates with a flicker-free direct current (DC) method, as opposed to any PWM at all brightness settings.
If you enable local dimming then a low amplitude oscillation, with the high peaks you see in this graph syncing with the refresh rate of the screen. So in this example at 160Hz the high peaks were every 6.25ms. This shouldn’t present any noticeable flicker in practice as the amplitude is very low, but we would not recommend turning local dimming on for office and general use anyway. There’s perhaps scenarios where it could help contrast in SDR movies, games and multimedia, but not for office use.
The wide colour gamut provides flexibility to work with a range of different colour spaces if you need to. The native wide gamut is useful for gaming, HDR and multimedia where you might well prefer the more saturated and vivid colours, and especially for HDR content which is mastered in a wide Rec.2020 colour space anyway. Having the ability to cover nearly all of the DCI-P3 and Adobe RGB colour spaces from this screen is great news if you want to work in either of those, and the provided emulation modes are pretty useful for this too. The lack of control over many of the OSD settings is a shame, and leaves us at the mercy of the factory setup, although the DCI-P3 mode is well configured for gamma and white point. Adobe RGB mode is too warm, with no easy way to correct that without a calibration device. sRGB emulation is also provided and generally well set up, although is a bit too cool in that mode. The other issue is that the clamping of the colour space is a bit too aggressive in all these emulation modes, leaving us with some under-coverage of the target gamuts. They are all adequate though for general use and work within those target colour spaces.
The spectral distribution at a calibrated 6500k is shown above, with the blue peak measured at 448 nm wavelength. This means it is not part of the Eyesafe certified range of products, as it does not have a blue peak that is outside of the supposed harmful range according to Eyesafe which is 415 – 455nm. There is a ‘Blue Light filter’ setting in the OSD menu which can be accessed via the ‘color adjust’ section. This is a slider from 0 (off) to 100 in increments of 25, and makes the image progressively warmer, but then also gets very yellow in colour. It’s usable at the 25 setting which measured 5605K and perhaps the 50 setting at 5071K, but any higher setting just looks too yellow in appearance (75 = 4733K, 100 = 4473K).
With a built-in KVM switch you can easily control an extra device such as a laptop, another desktop, tablet, or a phone using only a single set of a keyboard and mouse. With a simple toggle in the OSD menu, you can seamlessly swap controls to your second device for ultimate multitasking.
The screen has a decent range of ergonomic adjustments with tilt, height, swivel and also rotate available. Along with the common DisplayPort and HDMI inputs, there is a USB type-C with DP Alt mode and 90W power delivery which might be useful for some devices for single cable connectivity. There are also 2x USB ports and a headphone jack too, as well as some simple (and limited) integrated 2x 2W speakers on this model.
The M27P10 Pro is based on an IPS-type panel from panel manufacturer AU Optronics, their AHVA or so-called “Fast IPS” technology. The screen has a quoted 3ms G2G response time spec. Referring to the OSD menu we believed this screen to also offer a motion blur reduction mode via the ‘MPRT’ setting, but this is not the case. We will cover that more later.
There is a pretty high 160Hz native panel refresh rate and the screen features adaptive-sync for variable refresh rates (VRR) from both AMD and NVIDIA systems. This is available in the ‘gaming’ section of the OSD menu via the ‘FreeSync/G-sync’ option. Like we’d seen when we originally tested the Cooler Master Tempest GP27U, before the manufacturer provided a firmware update in early December 2022, the M27P20 Pro operates with a VRR range of 48 – 144Hz only. You cannot actually use the full 160Hz refresh rate range when using VRR, and you are blocked from being able to select 160Hz refresh rate from your graphics card control panel if you have adaptive-sync enabled in the monitor’s OSD. Only refresh rates up to 144Hz were available. Although given this is a 4K panel, pushing your frame rate in to these realms is going to be a challenge anyway. It is a shame you can’t use the full advertised 160Hz though at this time, it would be great if KTC could address this via a firmware update later on. The screen has not yet been certified under any of AMD’s or NVIDIA’s certification schemes according to their respective websites.
Within the OSD menu are a few ‘Game Assist’ settings for timer, crosshair and FPS counter in case you find those useful, and there is also a blur reduction mode available on this model which was not provided on the Cooler Master GP27U. There are also a range of preset modes available for things like FPS and RTS too.
Response Times and Motion Clarity
As discussed in our detailed article about Response Time Testing – Pitfalls, Improvements and Updating Our Methodology we are using an improved and more accurate method for capturing G2G response times and overshoot, based on figures that are more reflective to what you see visually on the screen in real-World usage. Our article linked above talks through why this is better and how we arrived at this improved method in much more detail.
We first of all tested the screen at its maximum 160Hz fixed refresh rate. As a reminder this is only available as a fixed refresh rate, you can’t use the full 160Hz when using adaptive-sync VRR. Through a series of visual tests and measurements we analysed the response time and motion performance in each of the 4 overdrive modes.
With overdrive turned off we had modest response times with 6.6ms G2G recorded, but free from any overshoot in this mode. The response times had poor refresh rate compliance though at 50%, showing they were not fast enough to keep up with the fairly high 160Hz when the overdrive is turned off. We moved up to the ‘low’ setting which had some decent improvements in motion clarity and reduced smearing on moving content. Response times had been improved now to 4.9ms G2G, and overshoot remained very low and was not visible during normal use and dynamic content. Moving up to the ‘Middle’ mode made the image a little sharper and response times had improved to 3.8ms G2G but you do get some moderate levels of overshoot, although these were what we’d consider “reasonable” in practice at this max refresh rate. There were some slight pale halos in some situations, and overall we didn’t really think there was much benefit over the ‘Low’ setting.
Perhaps unsurprisingly the maximum ‘High’ mode pushed things too far, only improving the G2G figure slightly to 3.3ms, but at the cost of some bad overshoot – now more visible in practice with pale halos and artefacts. We’d recommend sticking with the ‘Low’ mode at 160Hz for optimal performance, perhaps the ‘Middle’ mode if you don’t find the small amounts of overshoot a problem.
We then enabled adaptive-sync via the OSD menu and tested the screen across a variable refresh rate range at refresh rates of 60, 100 and 144Hz to see how the screen performed in these situations. The challenge in VRR situations is controlling the level of overshoot, and this isn’t easy without technologies like ‘variable overdrive’, usually reserved for screens using NVIDIA’s hardware G-sync module. That’s not featured here.
We started with the ‘Low’ setting for VRR, as anything higher showed very high levels of overshoot at the lower refresh rates. In fact even this ‘Low’ setting showed high and noticeable levels of overshoot at the bottom end of the refresh rate range, with pale and dark halos being evident in practice. We felt this ‘Low’ mode was ok for the upper end of the VRR range for ~100 – 144Hz, but anything lower and the overshoot becomes a problem.
We decided in the end to actually switch to the overdrive ‘Off’ mode which eliminated all the overshoot across the full VRR range. Response time performance was still pretty good and was adequate to keep up with the frame rate in all situations, even at 144Hz. This provides a simple single overdrive mode experience for VRR gaming as well which was good news. Perhaps the response times could have been a bit better, but the avoidance of all overshoot was definitely a positive here.
We have provided some motion clarity pursuit camera photos below comparing the ‘Low’ and ‘High’ overdrive modes when using 160Hz refresh rate. These are designed to capture real-world motion clarity in practice, as you’d see it with the naked eye. You can see the solid performance in the optimal ‘Low’ mode, and also the pale overshoot artefacts that start to appear if you were to use the ‘high’ mode. This overshoot in that mode gets worse by the way in that mode at lower refresh rates. Motion clarity will vary of course if you lower the refresh rate or use VRR and frame rate drops, this is more to demonstrate the best case motion clarity at the max refresh rate.
Gaming was sharp, crisp and clear thanks to the high 4K resolution, providing a very pleasing gaming experience. We will talk about HDR more in a moment, but the HDR gaming experience is also excellent,
Update 25 Nov 2023 – at the time of this review originally you were limited to using local dimming for gaming only at fixed refresh rates. You could not use VRR at the same time as local dimming unfortunately. KTC later released a firmware update which is available from their website that allows FreeSync (VRR) to be used at the same time as local dimming.
Another useful option perhaps for gaming is enabling the local dimming backlight even in SDR mode, which is a supported option on the M27P20 Pro. That can significantly improve black depth and contrast, improving darker areas and increasing the overall image quality. That’s something you could consider for SDR gaming too and it was nice to see access to the local dimming Mini LED backlight outside of HDR. The performance and colour setup in that SDR local dimming mode isn’t great right now but you can make a few tweaks in the OSD menu to get it looking better.
The OSD menu has a mode called “MPRT” (Moving Picture Response Time) which normally (always) implies that a motion blur reduction backlight mode is available. One which would activate a backlight strobing and help reduce perceived motion blur in practice. We activated this mode but were surprised to see that it didn’t actually activate any strobing at all, it seemed to instead activate the low amplitude “flickering” of the backlight that we’d seen earlier when we’d enabled the local dimming backlight (see the “general and office” section of this review).
Like when you enable backlight local dimming, the MPRT mode seems to activate a low amplitude and high frequency oscillation as shown above. This is not a proper on/off strobing of the backlight as you would find with all other motion blur reduction / MPRT modes. The larger peaks in this oscillation are in sync with the refresh rate so in this example they are every 6.25ms as we are running at 160Hz fixed refresh rate.
Activating MPRT mode seemed to boost the screen brightness a small amount by about 20 nits, but had no visible difference to motion clarity at all. You can’t use this “mode” (we can barely call it a mode) when VRR is active either, but it seems entirely pointless on the sample we are testing.
We spoke to KTC who confirmed that this has been updated in the firmware and should be a working mode in the current mass production version. If we are able to, we will get our firmware updated and come back to update this section of the review.
We should note here that we measured a super low input lag on the M27P20 Pro. There was a total display lag of only 2.00ms and with ~1.22ms of that accounted for by pixel response times, that leaves a signal processing lag of only ~0.78ms which is excellent. As a result the screen is perfectly fine for fast paced competitive games if you need from that point of view. There was no change to this lag result with local dimming enabled in SDR mode by the way.
The screen features offers a 4K resolution and support for high refresh rates including 120Hz, making it well suited to modern games consoles like the Xbox Series X and PlayStation 5. KTC have included two full-bandwidth HDMI 2.1 ports, delivering 48 Gbps speed and therefore supporting the max bandwidth capabilities of the two consoles. The support for 4K resolution (natively here) means you can make use of HDR from the Xbox where that mode is only available at 4K, which is of course one of the key capabilities of this screen. The Mini LED backlight comes in to its own here for HDR gaming, providing an excellent image quality and HDR experience. More on HDR in a moment.
|Native panel resolution||3840 x 2160 “4K”|
|Maximum resolution and refresh rate supported||4K @ 120Hz|
|PlayStation 5 support||4K @ 120Hz 4:2:2 chroma|
|Xbox Series X support||4K @ 120Hz 4:4:4 chroma|
|Virtual 4K support||Not needed|
|4K at 24Hz support|
|4K at 50Hz support|
|HDMI connection version||2.1|
|HDMI connection bandwidth||48 Gbps|
|HDMI-VRR (over HDMI 2.1)||?|
|Adaptive-sync (FreeSync) over HDMI|
|Auto Low Latency Mode (ALLM)|
|Ultra high speed HDMI 2.1 cable provided|
We confirmed via an Xbox Series X that 4K 120Hz works fine. There is no support for 24Hz but 50Hz is available. Only HDR10 content is supported as normal for a desktop monitor, not Dolby Vision. VRR was supported only when you have adaptive-sync enabled in the monitors OSD, which suggests maybe it’s using FreeSync over HDMI (supported for VRR from the Xbox) but not HDMI-VRR as a feature of HDMI 2.1. We do not have access to a PS5 to confirm whether or not that is the case, but it seemed that way from the way you could disable VRR from the monitors adaptive-sync setting. As we discussed earlier in the gaming and HDR sections you cannot use VRR at the same time as local dimming so if you want to game in HDR, we would recommend leaving adaptive-sync disabled anyway so that you can enable local dimming instead. It would be nice if the two could work at the same time though really as otherwise you’re missing out on one of the new console capabilities for gaming.
HDR (High Dynamic Range)
One of the key benefits of the M27P20 Pro is its 576-zone Mini LED backlight which sets it apart from common edge-lit local dimming monitors, which only have a very limited number of dimming zones, commonly 8 or 16. Mini LED backlights like the one used here provide a much better control over the image on the screen, being able to dim smaller parts of the image while brightening other areas to improve the contrast and dynamic range. Dark areas can often be dimmed so low that they are basically being turned off, while bright highlights can often be brightened to very high peak brightness levels. That’s one of the key benefits in using a direct lit backlight with many zones like this.
Each zone on this screen is responsible for around 14,400 pixels given the high 4K resolution which obviously isn’t as finite in control as something like OLED which has per-pixel level dimming control. Having said that, a Mini LED backlight is capable of reaching much higher brightness levels, including sustaining those brightness levels for larger screen areas, so each technology has its advantages and limitations. The 576 zones used here is very good though on a screen this size in the LCD market. This helps reduce blooming and halos in practice relative to screens with fewer zones. There can still be challenges on very specific content like star fields for instance, or scenes with very small bright areas, but that’s going to be hard for any FALD screen to handle and you really need something like OLED to avoid all halos.
Normal use HDR content looks very impressive, with images that pop with nice colours, some very bright areas, and very low levels of blooming and halos from what we could see. The ‘High’ mode seemed to work better here, making blacks look deeper and reducing some blooming you could see in the ‘standard’ mode. We tested the local dimming in both SDR mode (where it is available to use if you want) and HDR, and the blooming was consistently low. Halos were small and the Mini LED backlight did a very good job of brightening light areas, and darkening dark areas.
|HDR Technical Capabilities|
|VESA DisplayHDR certification level||DisplayHDR 1000 Certified|
|HDR formats supported||HDR10 Only|
|Local dimming||576 zone Mini LED|
|High number of local dimming zones||576 zone Mini LED|
|Increased peak brightness||1040 nits|
|Reaching advertised peak brightness||1000 nits advertised|
|Increased dynamic range (contrast) max||~58,000:1|
|Increased “local” HDR contrast ratio max||~2400:1|
|Wide colour gamut >90% DCI-P3||98.3% absolute coverage|
118.8% relative coverage
|10-bit colour depth support||Supported|
When you first enable HDR in Windows the image might look washed out, but this is because you also have to enable HDR in the OSD menu (set it to ‘auto’ instead of the default ‘off’), and then also enable local dimming to one of the two settings, standard or high. Once you’ve done that, the default Windows appearance in HDR mode is very good. There is only a single mode for HDR in the OSD menu and most of the settings are now unavailable.
HDR User Mode Default Settings
We measured the setup in HDR mode, with local dimming set to ‘High’ which we felt delivered the best picture quality and HDR performance. Nearly all of the OSD settings are now greyed out and unavailable.
Tracking of the PQ curve was good with only some small deviance in dark grey shades. The colour temp and white point were also good here overall, a little too cool in some grey shades giving rise to an average 6688K greyscale colour temp average, and a little too warm at the white point at 6288K. But overall a good performance which was pleasing, and avoids a super-cool HDR mode as many screens seem to have by default, in order to maximise brightness. We were pleased with the setup here.
Colour accuracy of HDR Rec.2020 colours is very good overall, thanks to the particularly wide colour gamut covering a decent 85.0% of the Rec.2020 colour space and the reliable colour temp. We had an average dE of 1.2 if we ignore than 100% red, blue and green shades which was very good.
Brightness capability varies a little depending on the local dimming setting you select. In the ‘standard’ mode, the peak brightness remains more consistent at different APL’s, including offering a higher brightness for smaller highlights. in the ‘High’ local dimming mode small highlights were not as bright though, and did not reach as high as the screen is capable of due to the local dimming nature, and the desire to avoid creating halos or blooming problems. We did feel though that the high mode looked better visually, reducing blooming and producing more consistent and deep blacks.
We measured a peak brightness of up to 1040 nits, which is in line with the advertised 1000 nits peak brightness. The peak brightness varied depending on the APL (size of bright content on the screen) with the highest brightness being achieved for 10% window sizes, before dropping down to a bit lower as that APL increased, and then pushing back up to the maximum again for 100% white screen.
The M27P20 Pro on the whole offered some very good performance, but is limited in a few areas that we would like to see improved if possible via a future firmware update. Gaming and HDR are the two target uses for this screen, and it does generally very well in both. For gaming there are good response times, a single overdrive mode experience for VRR, super low input lag and solid support for latest gen consoles too. The moderately high 160Hz refresh rate provides good motion clarity, and is a nice combination with the high 4K resolution that provides a sharp and crisp image.
On the HDR side the Mini LED backlight offers significant and very noticeable improvements over typical edge-lit “HDR” monitors, with a high peak brightness, very good local dimming, great contrast improvements and an overall strong performance for HDR content. The HDR mode while being almost entirely locked down from user tweaking did thankfully provide a very good setup. The ability to enable the local dimming backlight in SDR mode was also great to see, useful perhaps for contrast improvements in gaming and multimedia. There’s no doubt that the Mini LED backlight provides great benefits compared with limited edge-lit dimmed monitors.
Adaptive-sync is available for VRR, and of course this is a very useful feature when you consider the strain of powering 4K and high refresh rates. The problem is that at the moment you can only run up to 144Hz with adaptive-sync enabled and miss out on that small increase to 160Hz which is one of the areas which separates it from a wider selection of 4K 144Hz displays on the market. A minor sacrifice admittedly, but it’s disappointing to not be able to use the full spec of the screen with VRR. One other gaming related area that was poor was the ‘MPRT’ mode in the menu, which seemed to do nothing and offered no value.
In other areas the screen offers some decent all-round performance thanks to its IPS-type panel, and the image quality was very good with the 4K resolution. There’s a very wide colour gamut, great for HDR and multimedia, but more problematic for general usage. The provided emulation modes work mostly ok, although we would have liked to have seen access to all the OSD settings to make changes to white point and gamma more simple. Contrast ratio could have been a little better too, and the clamping of the smaller colour spaces in these emulation modes could have been less aggressive. The inclusion of modern connections like HDMI 2.1 and USB type-C was good to see, as was the KVM function that some people may find useful.
|Check pricing and availability in your region|
The M27P20 Pro provides some high end specs and features at a more affordable price point than older generation FALD/Mini LED backlit screens. The screen is expected to be available towards the end of January and has a RRP of $799.99. It will be available in the US via KTCplay.com and in applicable regions from Amazon (affiliate link). This puts it at the same price as the very similarly spec’d and designed Cooler Master Tempest GP27U (RRP $799.99), but at a decent saving compared with other available FALD/Mini LED displays. For instance the Sony Inzone M9 has a lower end spec and retails for ~$893 at the time of writing (144Hz only, HDR 600, 96 dimming zones). We can also compare it to older models like the Asus ROG Swift PG27UQ (with 144Hz, 384 zone FALD backlight, Native G-sync) from 2018 which had a significantly higher price point >$2500 USD and is still available in some regions. Clearly models like this KTC M27P20 Pro offer a far more reasonable price point if you’re after a decent HDR monitor.
|Mini LED backlight offers excellent HDR performance with high contrast and peak brightness||Missing support for VRR at maximum160Hz refresh rate|
|Very good response times, high refresh rate and low lag||MPRT mode does nothing of value on our sample, but should be working on new mass production stock|
|Nice extra features like USB type-C and KVM support||Emulation modes are limited in customisation and a bit too aggressive with colour space clamping|
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