Asus ROG Swift PG27UCDM

Introduction

4K resolution is finally here on a 27″ OLED screen! We know a lot of readers have been eagerly waiting for these displays to arrive. We’re reviewing today the brand new Asus ROG Swift PG27UCDM, a screen that is only today being announced formally after a short tease in December, but which we’ve been able to test and use over the last few weeks to bring you a full, detailed review straight away on day one. The PG27UCDM should also be showcased at CES 2025 next week.

This is the first time that a 3840 x 2160 “4K” resolution has been available on a mainstream 27″ sized OLED monitor. A few years ago there were some professional-grade OLED monitors released which had this size and resolution, using a panel from manufacturer JOLED. These had a 60Hz refresh rate only, and could not be considered “mainstream” or “affordable”, they were aimed at professional uses and content creation. There’s been a wide range of more mainstream and gaming OLED monitors released since 2022 in a selection of sizes, and until now the highest pixel density offered has been ~140 PPI on the 31.5″ 4K panels released last year from both Samsung Display (QD-OLED technology) and LG.Display (WOLED technology). That’s been good for those who want a larger screen size, and those 32″ class monitors have been extremely popular since they were released this year. For instance Asus have got two monitor options in this size, their ROG Swift PG32UCDM with a QD-OLED panel, and the ROG Swift PG32UCDP with a WOLED panel that we’ve reviewed.

Not everyone has the space for a 32″ screen or want an even higher pixel density, and many people have been waiting for a 4K resolution to be available from the 27″ segment. So far monitors of this size have been limited to 1440p (2560 x 1440) only. That time has finally come, with Asus making use of a new 2025 Samsung QD-OLED panel that we believe is part of their 4th generation technology. We will bring you more news and updates about Samsung QD-OLED in the near future as we expect more to be unveiled at CES next week. This new 27″ QD-OLED panel offers the highest pixel density available from an OLED monitor so far, at ~166PPI.

As well as the high 4K resolution, the PG27UCDM has a 240Hz refresh rate, and a wide range of connectivity options and new features. Asus have included the latest DisplayPort 2.1 connection with a proper, top-tier, UHBR20 80Gbps bandwidth. There’s also USB type-C and HDMI 2.1 connections. There’s support for Dolby Vision HDR as well as HDR10, and they’ve added some new technologies to the screen including their updated ‘OLED Antiflicker 2.0’ and a new ‘Neo Proximity Sensor’ which we will talk about more later.

Let’s see how the new screen performs in all our testing. Could this be the ultimate 27″ OLED monitor?

Key Specs and Features

• 27″ in size (more precisely 26.5″) with a flat format
• 3840 x 2160 “4K” resolution with 166 PPI pixel density
• Samsung Display QD-OLED panel with standard semi-glossy screen coating
• 240Hz refresh rate, 0.03ms G2G response time
• Adaptive-sync for VRR, certifications pending at the time of writing
• Extreme Low Motion Blur (ELMB) mode available (otherwise known as BFI)
• 1000 nits peak brightness spec for HDR, as well as VESA DisplayHDR 400 True Black certification
• HDR10 and Dolby Vision HDR format support
• 1x DisplayPort 2.1 (UHBR20, 80 Gbps), 2x HDMI 2.1 and 1x USB type-C (with DP Alt mode and 90W power delivery) video connections
• Headphone jack and 3x USB data ports, KVM switch, PiP/PbP support
• Fully ergonomic stand with tilt, height, swivel and rotate adjustments
• Custom heatsink and optimised cooling design means no need for active cooling fan
• ROG OLED Care Pro settings and ‘Neo Proximity Sensor’
• 3 year warranty including burn-in cover

Design and Features

The PG27UCDM comes in a familiar ROG styling, looking almost identical to other recent ROG screens from the front. It has a thin dark grey plastic edge around all 4 sides, along with a thin black panel border before the image starts. This border measures a total ~11.5mm along the sides, ~7.5mm at the top, and ~14mm along the bottom edge. There is a small “chin” on the bottom edge of the screen where the OSD control joystick is located on the back, with an ROG logo on the front that glows red normally, but can be disabled from the OSD menu if you want to.

From the back the screen is encased in a matte black plastic. It’s not the semi-transparent plastic casing that was introduced for their 480Hz PG27AQDP display previously, it’s opaque here like their previous models. There’s an RGB lighting logo on the right hand side as you can see from the photos provided which can be controlled or turned off from the OSD menu. There’s also an ROG logo projection on the bottom of the stand as is common for their screens.

The side profile is a little chunkier than some of their other recent screens like the PG27AQDP, largely because this model features an integrated power supply. You only need a normal kettle lead cable, there’s no need for any external power brick which we like. Normally the Asus OLED monitors have an external power brick.

There’s a very good range of modern connectivity provided on the screen with 1x DisplayPort 2.1 (UHBR20, 80Gbps), 1x USB type-C (with DP Alt mode, data and 90W power delivery) and 2x proper HDMI 2.1 ports for video. There’s also a 3 port USB hub and a headphone output available. We’ll talk a lot more about DP 2.1 in a moment and what that offers. An auto KVM switch function is featured for controlling two systems from a single keyboard and mouse setup. Picture In Picture (PiP) and Picture by Picture (PbP) modes are also supported for handling multiple inputs on the screen at once.

Like their other OLED monitors this screen is fan-less, thanks to the use of a custom heatsink to keep the components cool and so is silent in operation.

The stand provides a full range of ergonomic adjustments with tilt, height, swivel and rotate offered. These are mostly smooth and easy to re-position, although we found tilt to be stiff on our sample. The screen remains stable with basically no wobble at all as you move it around. The stand also supports the screen very well when you use the OSD joystick, without causing the screen to move around or wobble at all. It feels very strong and stable on your desk, Asus have really got these stands nailed now.

The OSD is controlled primarily through a small joystick toggle on the back of the screen’s “chin” section on the bottom edge. There are also two pressable buttons, one either side of the joystick. One gives you quick access to the ‘pixel cleaning’ function by default, while the other is the power on/off button. You can edit the left hand button via the menu to have a shortcut for something else though if you want. A nice touch is that if you press the power button, it prompts you to confirm you definitely want to turn the screen off, to avoid those accidental power-offs.

There is also some quick access to key settings via the directions on the joystick which you can customise in the menu, or if you press the joystick in you can enter the main menu. Navigation is quick, snappy and intuitive thanks to the joystick controller. There were a decent range of settings and options available too. The screen supports user-updatable firmware too.

OSD Menu
Joystick toggle controller
Quick and snappy
Intuitive to use
User updatable firmware

DisplayPort 2.1

Asus have included a top-tier DisplayPort 2.1 connection on this new screen, offering the full UHBR20 80Gbps speeds. If you’ve read any of our previous articles on the topic, or watched our recent video, you will know that DisplayPort 2.1 is a fairly messy standard at the moment and we’d encourage you to learn more about it if you’re unfamiliar.

By utilising the full speed capabilities of this connection, users with a compatible DP 2.1 graphics card will be able to power the screen at its native 3840 x 2160 resolution and 240Hz refresh rate with an uncompressed data signal, and without needing to use ‘Display Stream Compression’ (DSC). Considering DSC is a visually lossless approach anyway this won’t really impact image quality for 99% of users, but what it will do is help avoid some annoying bugs and limitations some people often have with DSC-enabled displays. That includes long delays and black screens when Alt-tabbing out of games, limitations when using multiple displays and daisy chaining, and missing support for features like NVIDIA DSR and DLDSR. Bypassing the need for DSC is an attractive option for some users and it’s nice to see DP 2.1 included here now that it’s becoming more widely adopted in the PC space.

You do need to keep in mind of course that to make use of this properly with the DP 2.1 UHBR20 speeds you are going to need a DP 2.1-capable graphics card. At the time of writing AMD have some UHBR20 cards in their professional range, but none with that highest tier in their consumer range (the max is UHBR13.5). NVIDIA don’t have any yet, although it’s very likely we will finally see NVIDIA launch these in 2025 and we expect this to be a big part of CES on the graphics card side of things next week. So graphics card support for DP 2.1 will improve this year, and the monitors are now starting to appear with this connection option where useful. It’s not necessary to power this spec, but it’s useful to some people for the reasons we’ve mentioned.

The DP 2.1 connection is of course backwards-compatible with DP 1.4 graphics cards so you can use DP 1.4 + DSC to run 4K @240Hz instead. However, you will need a DP 1.4 card that supports DSC to be able to power 4K @ 240Hz, and obviously a modern, high end card if you want to get anywhere near that for gaming. Asus provide a 1 metre length DP 2.1 UHBR80 cable (the cables are certified differently to the bandwidth tiers) in the box which is useful, although some people may find the length restrictive. This is another current challenge with DP 2.1, cable lengths are not very long still.

OLED Care

One challenge with OLED panels in general is the inherent risk of image retention and burn-in. It’s a technology more suited to dynamic and changing content, which is why these are largely positioned as gaming and multimedia screens. There is more of a risk of image retention if you are using these screens for lots of static desktop and office use though. Display manufacturers provide a range of measures to help mitigate that risk, and maintain the panel over time and we will talk about the OLED Care measures in a moment.

Asus include a 3 year warranty with the monitor, including burn-in cover which gives some added peace of mind around usage and image retention risks. This is the same as on their other recent OLED monitors.

To help mitigate the risks of image retention Asus provide an impressive and expanded set of OLED care options within the OSD menu under their ‘ROG OLED Care Pro‘ features. Familiar options include the pixel shift / screen move which moves the image slightly a few pixels at a time periodically (you can turn this off fully if you want). There’s also a screen saver which dims the screen if there is no change to the image for an extended period of time. There’s also an image cleaning cycle which will run automatically from time to time, or you can run manually in the menu if you want.

OLED Care and Warranty
Warranty period	3 years
Burn-in cover
Screen saver
Pixel / screen shift
Logo dimming
Taskbar detection
Motion sensor
Other OLED care features	Outer dimming control Global dimming control Boundary detection

There’s also some new options we saw on their PG27AQDP recently, but that older OLED screens in their range don’t offer. These include ‘outer dimming control’ and ‘global dimming control’. The former seems to activate the LG.Display CPC (Convex Power Control) feature which dims the edges of the screen but on this particular model does not seem to be too drastic and doesn’t seem to produce an obvious vignetting effect like it had on the PG27AQDP when we tested that. Global dimming control automatically identifies and adjusts the brightest areas of the screen to reduce the risk of burn-in.

An ‘auto logo brightness’ section includes options for ‘logo detection’, as well as ‘taskbar detection’ and ‘boundary detection’. Boundary detection dynamically detects the boundary of the black bars and reduces the brightness and also slightly shifts the pixel of the near borders.

Neo Proximity Sensor

One other new technology Asus have added to the screen is their Neo Proximity Sensor: This highly sensitive TOF sensor allows users to set their preferred usage distance. When the user steps out of range, the monitor will switch to a black image (i.e. turn off the pixels) to reduce the risk of burn-in, and restores on-screen content when you return to it. You can also customize the detection distance quickly and easily.

We’ve been saying for a while that we’d like to see more motion/proximity sensors on OLED screens, and it’s great to see Asus include that here, taking it a step further with the advanced distance detection which is great to see. Let’s hope this is included on all their future OLED monitors too.

Brightness and Contrast

For this testing we disabled the OLED care features in the OSD menu as those can have a small impact to screen brightness in certain situations. We would recommend enabling as many of those features as possible to mitigate risks of burn-in, although you may need to experiment for your particular usage to ensure none are distracting or problematic.

Uniform Brightness = OFF

Out of the box the screen operates with the ‘Uniform Brightness’ (UB) setting turned off, which is a feature we’ve seen many times now on Asus OLED screens that if enabled would help maintain a consistent screen brightness regardless of the content you show, the size of your windows or your Average Picture Level (APL). With this setting turned off you can see that the screens brightness varies depending on the APL and so you get fluctuations in brightness as you resize and move windows around or change your content. This can be distracting for office and desktop uses we find, although may not be as problematic for dynamic content like games and multimedia. You may want to try using this mode for SDR dynamic content as it could reach higher luminance levels than the uniform brightness mode.

With UB turned off the screen reaches up to a maximum 465 nits in SDR, although this drops down to 260 nits when you view a full white screen (100% APL) at the same setting. The Automatic Brightness Limiter (ABL) kicks in to dim the screen as the content changes. This applies even at lower brightness settings as you can see from the graph above. The minimum luminance the screen can reach (at a 10% APL measurement) was 23 nits which should afford you a good adjustment range for darker room environments.

• Useful reading – OLED Dimming Confusion – APL, ABL, ASBL, TPC and GSR Explained

Uniform Brightness = ON

Uniform Brightness mode behaves accurately with the same luminance being retained regardless of the APL window size being tested and the content being displayed. The screen can reach up to 263 nits at maximum brightness setting in this UB mode which is decent, and very similar to their 27″ 1440p 240Hz PG27AQDM and 27″ 1440p 480Hz PG27AQDP monitors, a few nits higher. This range of around 260 – 280 nits is common for an OLED monitor at the moment with uniform brightness behaviour. At the lowest setting the screen could reach down to a nice low 14 nits when using the UB mode, affording you very good flexibility for darker room conditions.

Black depth and contrast	Uniform Brightness OFF	Uniform Brightness ON
Max luminance	463 nits	263 nits
Min Luminance	23 nits	14 nits
Uniform / No ABL
Remains uniform in Windows desktop

We expect UB to be the mode most people will want to use for desktop and office SDR content, with a pretty decent range of brightness available, and the avoidance of any noticeable ABL dimming. The brightness remained consistent and uniform in Windows desktop as well, outside of test patterns.

Black Depth, Shadow Detail and Contrast

Black depth and contrast
Contrast ratio	~Infinite:1 (OLED)
Black depth (nits)	0.00
Shadow detail rating (SDR)	Excellent (RGB 1) in sRGB Cal mode Good (RGB 3) in other modes
Shadow detail adjustment control
Ambient light handling	Poor

One of the key benefits of an OLED panel is the fact it is capable of generating true blacks and a basically infinite contrast ratio. Each pixel can be fully turned off individually, and there’s no need for backlight local dimming here like there is on LCD’s. As a result, the black depth and contrast ratio can surpass all LCD panel technologies including VA panels by a long way. Blacks look inky and deep, and you get local contrast between different areas of an image.

Your ambient lighting may have some impact on perceived contrast ratio as it does with all screens, with this being more of a challenge on QD-OLED panels like that used here, than on competing WOLED alternatives. On QD-OLED panels in brighter rooms there is a fairly noticeable issue with raised blacks due to the panel structure and the fact that a polarizer is not used. The ambient lighting can cause inadvertent activation of the Quantum Dot layer on those panels, and blacks can start to look more grey or have a purple hue. We studied the impact of this in detail recently, which is linked below if you want to know more. In darker rooms or where you can more carefully control your light sources, it is not a major problem, but competing WOLED panels do fare better in a wide range of viewing conditions.

• Related content: The OLED Black Depth Lie – When Panel Type and Coating Matters

The near black shadow detail was very good out of the box and using this SDR test image we could just make out box 3 as the first we could distinguish before calibration in all of the general modes. This was even better in the ‘sRGB Cal’ preset mode where we could make out RGB box 1 as the gamma curve is differently configured in that mode. Shadow detail is something that can often be an issue on OLED panels but is seems to be very good here on the PG27UCDM in SDR mode, even at default settings.

Backlight or Panel Flicker

Flicker
Flicker free verified
PWM / flicker frequency	n/a

Like other OLED screens there is a minor fluctuation of the backlight, and in this case it operates in sync with the refresh rate, whatever you have that set at. Above it’s operating at 240Hz so there’s a small fluctuation every ~4.17ms. You can see on the graph above that the 0V would be an “off” state, so the amplitude of this fluctuation is minor, and does not produce any visible flickering or anything like that in practice. It’s not the same as PWM on an LCD monitor where the backlight is rapidly switched fully off and on when trying to dim the brightness level. Obviously being an OLED panel there is no backlight here anyway, and this minor fluctuation didn’t cause us any problems in real use and would be considered flicker free.

Default Setup (SDR)

The screen comes out of the box in the ‘Racing’ preset mode, with the ‘wide gamut’ colour space active and with ‘Uniform Brightness’ mode disabled. We tested this initial performance as normal.

Gamma tracking was very good overall and we measured a 2.19 average, following the target line very nicely across the greyscale. The colour temp and RGB balance on the middle graph were good too, with a good balance between the red, green and blue channels, although slightly higher in the red channel than intended leading to a slightly warm colour temp and greyscale. This resulted in a 6345K average greyscale temp and a 6325K white point, being a small 2 – 3% out from our target of 6500K. This still gave us with a very good overall greyscale accuracy though with a dE average of 0.9 measured.

The screen has a wide colour gamut which extends a significant way beyond the sRGB colour space in red and green shades, and results in a ~138.6% relative sRGB coverage calculation. This is a bit higher than competing WOLED panels (including the 27″ 480Hz Asus ROG Swift PG27AQDP for instance) which have a slightly smaller colour space of ~125% sRGB. It’s wider here thanks to the use of Quantum Dot coating on the QD-OLED panel. With the wide colour gamut active here, the accuracy of sRGB colours was poor, with a dE 4.1 average measured. This is normal for a wide gamut screen and to be expected and we will look if we can improve sRGB / SDR accuracy in a moment.

The native colour gamut of this panel matches the DCI-P3 reference quite closely as you can see from the bottom left CIE diagram, and we measured a 99.6% absolute coverage, but some over-coverage which reached 110.5% relative coverage. With that fairly close match, the accuracy of DCI-P3 colours out of the box was good, with a dE 1.6 average and 4.5 maximum measured. It deviated the most in red shades where the native panel gamut extended a fair way beyond the DCI-P3 reference space. This does provide a pretty accurate performance for content which might be mastered in this colour space, even out of the box. Overall there was a good default accuracy on this screen in the wide gamut mode which was pleasing.

Adobe RGB colour space compatibility

There is also good absolute coverage of the Adobe RGB gamut as well on this screen with 97.1% measured, although it extends a considerable way beyond that space (118.8% relative coverage) and so will need to be profiled using a calibration device to more accurately map to that gamut if you want to use it for professional or photography work which is commonly based on that colour space.

There is no provided Adobe RGB emulation mode on this screen like there is on some competing OLED monitors unfortunately, so you would need to be able to calibrate and profile the screen yourself for Adobe RGB content, for which you will need a calibration device. We’d like to see Asus add this on future screens alongside the sRGB and DCI-P3 modes.

sRGB Emulation Modes

The screen comes factory calibrated with dE < 2 in the ‘sRGB Cal’ preset mode according to the provided report accessible via the OSD menu:

There are actually two ways to achieve an sRGB emulation mode. There’s the ‘sRGB Cal’ mode as indicated by the calibration report, and then there’s also a colour space setting that can be used from within the other presets, for instance the default ‘Racing’ mode. We will test both approaches.

We measured the Racing mode first of all while selecting the sRGB colour space setting:

sRGB Colour Gamut mode (Racing preset)

This mode operates with a 2.2 power gamma and follows that reasonably closely overall, with 2.15 average measured. It was a bit lower in lighter grey shades which can result in some minor loss of light grey shade detail. Colour temp and white point strayed a little from our target, being a little too warm by 3 – 4%, which was slightly more than we’d seen in the ‘Wide gamut’ mode previously. This was overall quite similar to the default setup of the screen though when running in the ‘wide gamut’ mode as the only setting we’ve changed is the colour space.

With the sRGB colour space selected, we had good emulation and clamping of the target, with 99.7% absolute coverage measured, and only some minor over-coverage to 103.9% relative, but this was minor. Colour accuracy for sRGB colours was now very good in this mode with dE 1.4 average measured. This is a good and flexible way to use the sRGB emulation mode on this screen, actually giving you much better flexibility to alter other settings if you want than using the ‘sRGB Cal’ mode which we will test next.

sRGB Cal mode

This mode has been configured to the sRGB gamma instead of 2.2 gamma, but that does at least give you a simple preset mode to use if you specifically wanted to work with that very similar, but slightly different gamma curve for SDR and desktop content for any reason. This actually improves shadow detail even further than the already very good other modes, with RGB greyscale box 1 now being visible. It’s the near-black gamma that is different in the sRGB gamma curve, and that’s helped here. The gamma is a little lower than intended though for mid to light grey shades as it had been in the other sRGB approach, losing some shade detail.

White point and colour temp remained similar to how they were before in the default ‘Racing’ mode, with a small 2% deviance for both but a very good greyscale accuracy with dE 1.1 measured.

The native colour space has been clamped back here quite close to the sRGB reference, basically the same as the sRGB colour space mode when using other presets like the ‘Racing’ mode we measured above. With the approximate sRGB colour space in play, we had similar colour accuracy for sRGB content with a dE 1.6 average measured.

The main problem with this mode is that nearly all the OSD settings are locked, so there’s no way to customise anything if you wanted to apart from (thankfully) the brightness setting. We think most people will probably prefer to use the other modes and simply change the colour space if they want to use the sRGB emulation.

Calibration

Calibration and profiling can produce some very good overall results and could be useful though if you wanted to operate the screen within its native wide gamut mode, but then map the colour space back to something else like sRGB or Adobe RGB for instance for colour-aware applications (e.g. Photoshop). You would need a suitable calibration device and software.

In this section the screen 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 to map back to sRGB in this instance. Overall the calibrated results were excellent as you’d hope. You can find our calibrated settings and ICC profile in our ICC profile database now.

General and Office

Finally a 4K resolution on a 27″ panel

This is the first time that a 3840 x 2160 “4K” resolution has been available on a mainstream 27″ sized OLED monitor. A lot of users have been waiting for this spec, offering an increased pixel density of ~166 PPI, the highest currently available from an OLED monitor panel. On a screen this size 100% OS scaling is probably going to be too small for most people, with very small text so you can’t make full use of the additional resolution desktop space. You will likely want to run at either 125% or perhaps 150% scaling which will give you an equivalent desktop resolution space of 3072 x 1728 resolution, or 2560 x 1440 respectively. The 150% scaling option returns you to the same desktop space as a normal 1440p monitor, but because of the increased pixel density the image is sharper and clearer. Running 125% scaling would give you a 44% increase in desktop area which is a decent upgrade from 1440p-only monitors of this size and is a viable option on a screen this size.

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 and 100% scaling. If you have the necessary software and operating system then the 4K resolution provides a very sharp and crisp image though.

Not everyone will necessarily want or need 4K resolution and may be perfectly happy with the wide range of 2560 x 1440 resolution 27″ OLED monitors on the market. Those would avoid any complications with scaling and software support, will save you some money, and are also a much lower drain on system resources for gaming and other multimedia. At least now there is a choice though for those who do want 4K res on a 27″ monitor.

• Useful reading: The Obsession with 4K and Do You Need it on a New Monitor?

Sub-pixel Layout and Text Rendering

Because of the somewhat unusual triangular shaped RGB sub-pixel layout, slight text fringing has been a challenge on older QD-OLED monitors. This has been improved with Samsung’s Second Generation and Third Generation panels where the sub-pixel shape has been updated in most cases. Although to make life complicated the sub-pixel shape isn’t actually tied directly to QD-OLED generations, as evident by their 34″ ultrawide 240Hz panel which is officially part of their 2nd gen panel line-up with associated gen 2 technologies, it was produced in 2024 alongside their gen 3 panels, but still has the older diamond-shaped sub-pixels from their original gen 1 panels. Anyway, the above graphic explains the pixel shape for each of the currently produced Samsung QD-OLED monitor panels in each size.

For this 27″ 4K panel the squarer sub-pixel shape has been used which helps improve text clarity. Combined here with the super-high pixel density it effectively eliminates any remaining issues with text clarity. It was very hard to see any issues with fringing on this panel, and we expect the vast majority of people will see absolutely no issue with it for text and office work. The higher pixel densities being introduced in the QD-OLED panel space have really helped overcome the oddities with the sub-pixel layout.

Screen coating

The screen coating of the QD-OLED panel is the standard “semi glossy” finish. It retains most of the clear and crisp picture quality of a fully glossy solution, but without having major reflections to worry about thanks to an added AR (Anti Reflection) film. In certain situations and lighting conditions you will certainly see more reflections than a matte coated screen and light isn’t diffused in the same way, but during typical day to day usage, even with a window facing the screen we didn’t find it too bad at all.

The coating can make colours and blacks pop a bit more, in the right lighting conditions but you need to be mindful of your lighting levels and positioning to avoid raised blacks, a problem that impacts all QD-OLED panels. We like the coating balance here personally and prefer it to the matte AG coating of WOLED panels at the moment.

• Further reading: Glossy vs Matte – OLED Panel Coatings Compared

Screen Brightness

	Brightness
Maximum brightness (SDR)	263 nits
Minimum brightness	14 nits
Uniform brightness behaviour
Flicker free

The screens brightness should be fine for most users, reaching up to around 263 nits maximum in SDR applications and without the need for ABL to be used at all when using the ‘Uniform brightness’ mode which we recommend for these kind of uses. This is great news as it ensures a consistent and stable brightness no matter the content you view, or no matter your window sizes. The screen can’t reach quite as bright as a few other modern OLED panels (which reach 270 – 280 nits in some cases), but unless you need to use the screen in a very bright room or are used to running your existing screen at high brightness settings, it should be fine still and is very close anyway. The lower adjustment is decent for darker room environments.

Useful Office Features

	Features
USB type-C connectivity (DP Alt mode)
USB type-C power delivery	90W
KVM switch
PiP and PbP support
USB data ports
Easy access USB data ports
Integrated speakers
Audio output / headphone out
Mic input
Ambient light sensor
Motion sensor
Stand adjustments	Tilt, height, swivel, rotate
Tripod socket
Fan-less design

The screen has a good range of additional features and connections. There’s 1x USB type-C connection, a KVM switch function and USB data ports which are handy. There’s no integrated speakers on this model, but there is a headphone connection. The fan-less design and the new motion sensor are welcome for these kind of uses too.

One annoyance is with the PiP/PbP function, which only works on this screen when DSC is disabled. When you activate these modes, you get a warning pop-up about this and the screen disables DSC for you. That severely restricts your available refresh rate and colour settings, limiting you to 4K 120Hz 10-bit, but via 4:2:2 chroma sub-sampling when using DisplayPort. Or 4k 120Hz 10-bit 4:4:4 chroma over HDMI 2.1 if you’ve got a graphics card with it. The alternative for DisplayPort connections is to drop to 4K 97Hz which can then support 8-bit 4:4:4 chroma. Anyway, using the PiP/PbP modes forces DSC to be turned off, but when you then disabled PiP/PbP, you have to go back in to the ‘system setup’ section of the OSD menu to turn DSC back on again yourself. It’s a bit annoying and restrictive. This may be the same on other recent 4K 240Hz screens from Asus too in fact, it’s not something we specifically tested previously but we spotted it here.

Blue Light and Eye Care Modes

The native panel spectral distribution is shown above at a calibrated 6500K white point, where the blue peak is at 457 nm. This means it is part of the Eyesafe certified range of products where there is a supposed harmful range between 415 – 455nm which is a change for QD-OLED panels which have previously had the blue peak at ~453nm. This was an unexpected surprise actually, and presumably something Samsung Display have been updating with their newer panels.

There is a ‘Blue Light Filter’ setting in the menu with 4 levels available, but they are only accessible when you have Uniform Brightness disabled for some reason, which might make them a little pointless for office applications where you will probably want to have UB enabled. These modes get progressively warmer in appearance and we measured 5605K (level 1), 5438K (level 2), 5227K (level 3) and 4943K (level 4). The level 4 setting also has a locked brightness capped at a setting of 22 (with UB off).

Gaming

The PG27UCDM is heavily focused on its gaming capabilities. The screen uses a QD-OLED panel which is well-known for its near-instant response times. As a result it does not need to use overdrive technology in the same way as a desktop LCD panel would, and there aren’t any controls for the response time or overdrive in the OSD menu as they’re not needed. Asus, like other OLED display manufacturers quote a very low 0.03ms G2G response time in their spec, and while true <1ms G2G should be expected from this technology this is a little unrealistic.

(at native resolution)	Refresh Rate
Maximum Refresh Rate DisplayPort	240Hz
Maximum Refresh Rate USB type-C	240Hz
Maximum Refresh Rate HDMI	240Hz
VRR range	48 – 240Hz
ClearMR certification tier

You will of course need a very powerful system and graphics card to get anywhere near 4K @ 240Hz, although you may of course want to play older games or at lower settings where this can be more achievable. There’s also plenty of future-proof room there as other system components are improved and updated over the coming years and new graphics card capabilities are developed.

The 4K resolution provides a super sharp and crisp image, with more detail and clarity than lower resolution panels, especially with the very high 166 PPI pixel density on a 27″ screen like this. It also makes the screen well-equipped to handle modern 4K gaming from PC’s and consoles. With the support for DisplayPort 2.1 UHBR20 speeds you can avoid the need for DSC to be used if you have a DP 2.1-capable graphics card and run the screen with an uncompressed signal. This should in theory help avoid DSC-related issues like black screens when alt-tabbing out of games, limitations with daisy chaining and multiple screens. As we discussed earlier though, you will need a DP 2.1 capable graphics card to take advantage of this uncompressed signal. DP 1.4 cards can be used as well, but will need to support DSC to be able to power the screens 4K @ 240Hz.

Variable Refresh Rates (VRR)

	VRR capabilities and Certifications
AMD FreeSync certification	FreeSync Premium
Native NVIDIA G-sync module / G-sync scaler
NVIDIA ‘G-sync Compatible’ certified
VESA ‘AdaptiveSync’ certification	AdaptiveSync 240
HDMI-VRR (consoles via HDMI 2.1)

To help support the hefty demands of 4K @ 240Hz the screen features adaptive-sync, giving Variable Refresh Rate (VRR) support for both NVIDIA and AMD systems which is great news. The screen is certified under the AMD ‘FreeSync Premium’, VESA ‘AdaptiveSync 240’ and NVIDIA ‘G-sync Compatible’ schemes.

VRR flicker

VRR flicker is a very tricky area to quantify and measure on a monitor. All OLED panels can suffer from VRR flicker, it’s an inherent challenge with these panels. But whether or not you will experience that or see it depends on so many factors, it is hard to standardise a sensible and meaningful testing approach. Whether you will experience flicker can depend on the screen itself, your system and graphics card, the game you’re playing, the type of scene in that game, your settings, and also the frame rates you are achieving in the game. A large number of variables as you can see.

Large swings in frame rates within the VRR range seem to commonly trigger flicker though, especially in darker scenes and often on loading screens. At TFTCentral we are not keen on creating a “stress test” approach to testing VRR flicker; as just because a screen can show flicker in the most extreme scenarios and synthetic tests, doesn’t mean that it will show flicker in normal, typical situations or for your usage.

We are still exploring potential ways to measure and quantify flicker in the future in a meaningful way for our readers but even if we can standardise some testing, we clearly can’t test every scenario and game, and our system will be different to your system. We also don’t have the time and bandwidth to play lots of games around our testing and reviews, so it’s of questionable value to comment on whether we experienced VRR flicker or not. We would encourage you to read user comments when this screen is released, preferably based on the games you are going to play. Although always take feedback with the caveat that every scenario and test system will be different.

For now one standardised approach we are exploring as a starter is to use this small ‘VRR Flicker test’ application. The program creates a full-screen OpenGL context on the monitor in the desktop resolution, renders a gradient from mid grey to black and then varies the framerate up and down between 1/120th and 1/40th of a second. The unstable frame rate can cause flickering on many displays. We tested this application on this monitor and saw some occasional flickering across the screen, and some artefacts produced in the darkest shades near black.

Asus OLED Antiflicker 2.0 with Dynamic Brightness Algorithm

For the new PG27UCDM Asus tell us they have improved VRR flicker reduction by up to 20% over previous QD-OLED monitors, dynamically adjusting brightness with refresh rate changes to maintain stability. We are hoping to learn a lot more about this technology at CES so we will hopefully be able to provide a more detailed explanation of how it works in the near future. Keep an eye on our site for an upcoming article on this technology.

Asus provide an additional setting in the OSD menu, oddly within the ‘image’ section instead of the ‘gaming’ section. This ‘OLED Anti Flicker’ setting has options for off, medium and high. We tested this using the VRR flicker test application above and saw some small improvements to overall screen flicker when moving up from the medium to high modes. It didn’t eliminate 100% of the flickering, but it did offer some improvements. It does this by restricting the VRR range that is available, therefore in theory reducing the potential frame rate swings that you might be impacted by. Oddly the ‘off’ mode showed the least flicker in that particular test.

As we said before, it’s hard to know whether your system and your game will cause flickering or not. These extra settings could help a bit and it’s good to see them offered. Capping your frame rates, or perhaps even just turning VRR off altogether are other options you could consider if flickering does become an issue for you.

Gaming Features and Settings

NVIDIA DSR / DLDSR

	NVIDIA DSR / DLDSR
Support with DSC active
Support with DSC disabled
Max resolution and refresh rate supported over DisplayPort (with DSC disabled)	4K @ 97Hz, 8-bit, 4:4:4 (RGB) full chroma 4K @ 120Hz, 10-bit, 4:2:2 chroma
Max resolution and refresh rate supported over HDMI (with DSC disabled)	4K @ 120Hz, 10-bit, 4:4:4 (RGB) full chroma

At the moment NVIDIA cards only feature DisplayPort 1.4, and so the future support for these features over DisplayPort 2.1, without DSC being needed, is hypothetical, but expected. We obviously can’t test and confirm that at this time, so we can only consider if and how these technologies are supported from current NVIDIA DisplayPort 1.4 cards.

We tested support for NVIDIA DSR / DLDSR which can sometimes work on monitors with DSC (Display Stream Compression), but not always. We found that these technologies were not available on this screen by default, even if you drop down to a lower refresh rate like 60Hz or a lower resolution.

There is a setting in the OSD menu to disable DSC if you want which gives you access to these NVIDIA DSR and DLDSR features. However, you will be significantly limited in the available refresh rate without DSC in use. The maximum you can now run the screen at would be 4K @ 120Hz, but over DisplayPort that will force you down to 4:2:2 chroma sub-sampling regardless of whether you select 10-bit or 8-bit colour depth. A reduced chroma level is likely to be visible in many situations, especially office applications and on coloured text. You can lower the refresh rate to 97Hz which is the maximum that will allow you to use 4:4:4 RGB chroma, at an 8-bit colour depth over DisplayPort. That avoids chroma sub-sampling if you were going to turn DSC off in order to get access to DSR / DLDSR.

If you have a graphics card with HDMI 2.1 output and you specifically want to use DSR technologies, you will still need to disable DSC in the menu but you would be better off using that connection. This allows the maximum 4K 120Hz but at 10-bit and 4:4:4 chroma as the connection has more bandwidth than DisplayPort 1.4. Regardless of which connection you use, to make use of DSR you’d need to sacrifice refresh rate a lot which we don’t feel is worthwhile for a lot of users.

DSR/DLDSR is a lot less relevant on this screen anyway as it is already natively 4K, and has a high pixel density. DSR / DLDSR is more commonly aimed at use on lower resolution monitors with 1080p or 1440p resolution, where you can upscale the input image to 4K to improve sharpness and image clarity. In theory you could use it here to push beyond 4K but with the panel already offering a high resolution and density natively, its a lot less relevant. There is no benefit by the way in running the screen at a lower resolution and using DSR to upscale to 4K, you might as well just run at 4K natively which should be equally / less demanding on your system anyway.

	Other Features
Black Frame Insertion (BFI)	ELMB function
Gaming extras	FPS counter Crosshair Sniper mode Timer Stopwatch Shadow Boost
Emulated gaming sizes	24.5″ screen size

There’s a familiar range of gaming extras in the OSD menu as listed above. The Shadow Boost seems to impact mid grey shades more than dark grey shades in our testing, apart from when using the maximum ‘Dynamic’ mode, so this may be of lesser value in darker games than perhaps you might like.

Response Times

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.

The above G2G response times are consistent at all refresh rates, including 240Hz, 120Hz and 60Hz and during VRR situations with changing frame rates. Thanks to the OLED panel the response times are super-fast and near-instant, with an average of only 0.50ms G2G measured. The best case was an incredibly impressive 0.31ms and the overall response times were as expected from an OLED panel. All transitions can keep up easily with the frame rate demands of even 240Hz, and there was also no visible overshoot evident which is great news too, so overall there was nice and clean pixel transition times.

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Our thanks to the following manufacturers for support in the build of our new test system:

	AMD Ryzen 9 7950X | Buy AMD Ryzen 9 CPUs here on Amazon
	Asus ProArt B650-Creator | Buy Asus B650 motherboards here on Amazon
	Corsair DDR5 RAM | Buy here on Amazon
	Corsair H100i Elite Capellix AIO cooler | Buy Corsair coolers here on Amazon
	Corsair iCUE RGB Elite Fans | Buy here on Amazon
	NVIDIA RTX 3090 | Buy NVIDIA RTX graphics cards here on Amazon

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Motion Clarity

We captured some pursuit camera photos of the screen at a variety of refresh rates, designed to capture real-world perceived motion clarity. This gives you a good indication of how the screen looks in real use, beyond G2G response time measurements.

The motion clarity is as expected from a 240Hz OLED monitor, and all OLED screens of this refresh rate look visibly the same, including the Asus ROG Swift PG32UCDM for instance which is the 32″ alternative to this screen. Motion clarity is very good at 240Hz on these kind of panels, actually equivalent to a good 360Hz LCD monitor in practice.

Here’s some further comparisons of the motion clarity with other common OLED refresh rates, including the 360Hz QD-OLED panels which are currently available in 27″ screen size at the moment like the MSI MPG 271QRX and Dell Alienware AW2725DF for example; and the new 480Hz 27″ WOLED panels like the Asus ROG Swift PG27AQDP.

The motion clarity is improved further as you move from 240Hz up to 360Hz, and then a little more as you move up to 480Hz, although to benefit from this you’re going to have to be able to power very high frame rates from your system. This screen obviously obvious has a limit of 240Hz and is aimed more at gamers who don’t necessarily need or want those super top-end specs. It’s still a very impressive gaming experience at 240Hz on an OLED with great motion clarity.

Extreme Low Motion Blur (ELMB) aka BFI

Like the 32″ PG32UCDM and other recent Asus OLED monitors, the PG27UCDM has an added BFI (Black Frame Insertion) mode for blur reduction. Asus call this ELMB (Extreme Low Motion Blur) and it’s the alternative to a strobing motion blur reduction backlight you might find on some LCD monitors. Rather than the backlight being strobed off and on rapidly (because there is no backlight on an OLED panel), a black frame is inserted periodically in to the image instead. With the panel manufacturers not offering native panel support for this feature Asus have introduced a scaler based BFI function on several of their new OLED monitors, including this model.

ELMB activation and operation

We tested this on the PG27UCDM and confirmed that it is available via the OSD menu, but has some limitations. Firstly this is only available when using a fixed 120Hz refresh rate. That’s because the panel still operates at it’s native 240Hz behind the scenes, but a black frame is inserted for half of the frames, giving you 120Hz. There’s no support at the moment to use BFI at any other refresh rates like 60Hz or 100Hz for instance. It also cannot be used at the same time as variable refresh rate, only for a fixed 120Hz input. It can also only be used in SDR mode, not in HDR.

Uniform Brightness mode is also unavailable when you enable ELMB, although we confirmed that the screen does actually operate with a uniform brightness behaviour in this mode anyway without any ABL dimming.

Motion Blur Reduction Mode
Motion Blur Reduction mode / BFI
Refresh rates supported	120Hz only
60Hz single strobe operation
Blur reduction available with G-sync/FreeSync VRR
Available in SDR mode
Available in HDR mode
Viable with games consoles
Brightness capability (SDR, max refresh rate supported)
Independent brightness control available
Motion blur OFF – Max brightness	~263 nits (uniform brightness mode)
Motion blur ON – Max brightness	134 nits

The fact it is only available at 120Hz does make it a bit of a pain to use in practice, as if you were gaming or using the screen generally at 240Hz for instance, maybe using VRR too, if you decide you want to use ELMB instead you have to manually change your graphics card refresh rate to 120Hz first, then disable VRR, and only then can you activate ELMB. Then if you want to return back to 240Hz or VRR you have to reverse those steps. This makes it pretty inaccessible and cumbersome to get to. It would be nice if you could just enable ELMB whenever from the OSD menu and that then moved you to 120Hz mode and disabled anything like VRR that cannot be used at the same time.

No doubt there are a lot of limitations with how this is implemented on the scaler side at the moment, but in the future we’d like to see some simpler controls and activation steps for this feature. At the moment it feels a bit “experimental” in the user experience, likely because it is a new and custom feature.

We confirmed that at 120Hz the black frame in inserted in sync with the refresh rate, every 8.33ms as shown above with a 50:50 duty cycle.

ELMB Performance

With ELMB enabled, the brightness control is available all the way up to 100, which is good as on the PG32UCDM model when we tested it, this had been restricted to 70 for some reason. On this screen the luminance can be adjusted up to 134 nits which is fairly limited but better than the 96 nits of the 32″ PG32UCDM model. Overall this means that the ELMB mode is reasonable in brightness, but may not be able to reach bright enough for some users who prefer to have their screen set brighter. Thankfully unlike some of their previous OLED monitors with this feature, the brightness setting is remembered independently from the off state, so you don’t need to worry about changing that each time you want to turn it on or off.

Above is the perceived motion clarity of the screen at 120Hz and 240Hz when running in normal mode, and then also at 120Hz with ELMB enabled. You can see that the motion clarity looks pretty similar at 120Hz with ELMB as it does at 240Hz with the mode turned off. This is to be expected given the 50:50 duty cycle of the BFI function really. This clarity is the same across the entire screen though thanks to the super-fast response times of the OLED panel, you don’t need to worry about which area of the screen is the cleanest and clearest, like you do on an LCD screen with a strobing blur reduction backlight.

Motion Clarity Equivalence
120Hz ELMB = 240Hz regular

Using ELMB mode

So when is this mode useful? It can help improve perceived motion clarity at 120Hz for sure, and so might be useful if you can only power up to around 120 fps from your system. This might be common given the huge system demands of reaching 4K 240Hz. You could instead game at 120Hz and use ELMB in that mode to bump your motion clarity up to the equivalent of 240Hz – a shortcut if you will to reaching 240Hz-like motion clarity. Also if you’re playing a game that doesn’t even support the higher refresh rates, then this is a good way to give yourself a motion clarity bump.

On these new top-end gaming OLED displays ELMB / BFI could be a really useful stop-gap for improving motion clarity while your other system components and graphics cards catch up, and while you wait to be able to really power 4K at 240 fps. Keep in mind you do have to make some sacrifices in other areas like the loss of VRR, a more limited brightness, potential flickering / eye strain, and it’s a bit fiddly to turn on and off. But for those who want a nice boost in motion performance and sharpness it’s a very useful option.

If your system is more powerful, you can get the same motion clarity if you stick with 240Hz and can reach up to 240fps, along with the improved latency and frame rates that running that high will offer. You can also then use VRR and other settings, and reach better brightness levels, so if you can power the screen at that level you will probably want to try and just use the screen at 240Hz instead where possible. Had this BFI mode also been available at 240Hz, it could have offered another step up in motion clarity, reaching 480Hz-like levels. Sadly it’s only possible at half the native refresh rate at the moment.

Another use case might be if you are disabling DSC from the menu in an effort to use DSR / DLDSR features. You are restricted to 120Hz maximum in that situation anyway, and so you could consider using ELMB to give you a motion clarity boost from there. All in all we can see decent value in the ELMB feature here.

ELMB Console Support

One other use case where this could be potentially useful is for console gaming with ELMB available when you’re running the console at 120Hz refresh rate. You would have to live without VRR, and a more limited brightness too, but it’s available to use for consoles which is good news.

This had not been possible when we tested ELMB on the 34″ ultrawide PG34WCDM model, as on that screen you needed to use the screen’s aspect aspect ratio controls in order to avoid image stretching and allow the 16:9 aspect ratio of the console. ELMB was not available at the same time as aspect ratio control. Even if it had been available at the same time as the aspect ratio controls, 120Hz also only seemed to function at 1080p from the console in our testing on that screen, so that’s quite limiting anyway. Using ELMB on the PG27UCDM with a console is more viable thankfully thanks to its native 16:9 aspect ratio (so no need to use the aspect ratio controls in the menu), and support for 4K 120Hz inputs.

Lag

Read our detailed article about input lag and the various measurement techniques which are used to evaluate this aspect of a display. The screens tested are split into two measurements which are based on our overall display lag tests and half the average G2G response time, as measured by our oscilloscope. The response time element, part of the lag you can see, 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 of the lag you would feel from the display. We also classify each display as follows:

Lag Classification (updated)

• Class 1) Less than 4.17ms – the equivalent to 1 frame lag of a display at 240Hz refresh rate – should be fine for gamers, even at high levels
• Class 2) A lag of 4.17 – 8.33ms – the equivalent of one to two frames at a 240Hz refresh rate – moderate lag but should be fine for many gamers. Caution advised for serious gaming
• Class 3) A lag of more than 8.33ms – the equivalent of more than 2 frames at a refresh rate of 240Hz, or 1 frame at 120Hz – Some noticeable lag in daily usage, not suitable for high end gaming

There is an extremely low lag on the PG27AQDP measured at 0.33 ms total display lag, and leaving us with only 0.21 ms of estimated signal processing lag. This is perfectly fine for competitive gaming. Even at a fixed 60Hz refresh rate the lag wasn’t much higher, measured at only 5.62ms total lag on this screen. That’s a lot better than many other high refresh rate monitors, including many of Asus’ other OLED monitors in fact. Remember that it is the lower number (0.33ms) that will be relevant for VRR gaming as well, even where frame rates drop. The 60Hz figure is only applicable for fixed 60Hz input sources.

Console Gaming

The screen features offers a native 4K resolution and support for high refresh rates including 4K @ 120Hz, making it very well suited to modern games consoles like the Xbox Series X and PlayStation 5. Asus 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 OLED panel with its amazing contrast and blacks comes in to its own here for HDR gaming, providing an excellent image quality and HDR experience. More on HDR in a moment.

	Console Gaming
Native panel resolution	3840 x 2160 “4K”
Maximum resolution and refresh rate supported	4K @ 120Hz
Virtual 4K support	n/a
4K at 24Hz support
4K at 50Hz support
HDMI connection version	2.1
HDMI connection bandwidth	48 Gbps
HDMI-CEC auto switch
HDMI-VRR (over HDMI 2.1)
Auto Low Latency Mode (ALLM)
HDR10 support
Dolby Vision HDR support
Integrated speakers
Headphone connection
Ultra high speed HDMI 2.1 cable provided

We confirmed via an Xbox Series X that 4K 120Hz works fine, along with support for 4K 50Hz and 24Hz content and VRR which is very useful. Like the PG32UCDM there is also support for Dolby Vision HDR content on this screen which is still rare in the monitor market, accessible if you switch the ‘HDR format’ option to Dolby Vision in the OSD menu. HDMI-CEC is included as well using the ‘Power Sync’ setting in the OSD menu to auto switch to the HDMI input when a console or other external device is powered on.

Note that there are no integrated speakers on this model unlike some competing screens, and so you’ll need to connect headphones or some kind of external soundbar/speaker system when using a console. That’s one potential gap for the PG27UCDM if you’re looking to play console games or connect other external devices but that’s the only thing it’s missing. Great overall console support here from Asus.

HDR

Being a QD-OLED panel, the PG27UCDM is well equipped to handle HDR content with its per-pixel level dimming allowing for true blacks, a basically infinite contrast ratio and the avoidance of all blooming and halos. In these regards it can easily surpass any Mini LED backlit LCD monitor. However, it cannot reach the same luminance levels as Mini LED screens, and carries a “peak brightness” spec of 1000 nits, which will then also lower as the content on your screen changes and the APL increases which is normal on this technology. This is one key area where Mini LED screens can look brighter and deliver a more impactful HDR experience.

As it uses a QD-OLED panel it can suffer from the reduced perceived black depth and contrast that are a challenge for this technology. You need to be mindful of your ambient light levels and the position of those light sources. Ideally the light sources would be behind the panel, or you’d be viewing HDR content in a very dark room. That will also help minimise glare and reflections on the screen’s semi-glossy coating.

HDR modes and Settings

There’s quite a few HDR modes available on this screen, as well as support for two different HDR content formats – HDR10 and Dolby Vision. Asus have thankfully included an option to switch between HDR10 and DV modes in the menu, to avoid confusion and buggy behaviour with how Windows handles HDR. Dell had to add this setting later on after they launched the AW3225QF as the DV support was causing problems from Windows.

• Within the HDR10 mode there are presets for Gaming, Cinema, Console and ‘DisplayHDR 400 True Black’ available.
• There is an additional toggle option for ‘Dynamic Brightness Boost’ available when using the HDR10 Console mode only.
• When you enable Dolby Vision (DV) then there are modes for Bright, Dark and Game.
• You can also enable the ‘adjustable’ HDR setting if you want, which gives you access to change the brightness, contrast and colour settings if you want to make some tweaks. Note that on this model the brightness is set at its maximum level of 100 by default anyway.

So, there’s a lot of different modes and configurations to test and consider here. We will do our best to provide comparison data and commentary in the following sections.

Dolby Vision testing and usage

One thing to keep in mind is that the Dolby Vision (DV) modes are aimed at handling DV content, but such content is extremely limited and difficult to get working from a PC at the moment. Some modern devices like the Xbox Series X support DV content, so you could of course enable that mode on the monitor if you want to make use of that for the Xbox. What you can also do though is force the screen in to DV mode via the menu, and then when you input a normal HDR10 signal (like Windows HDR), it will still operate within those DV modes. We saw this PC content “hack” provide a brighter HDR mode option on the Dell Alienware AW3225QF previously, and so there’s the potential to use these DV modes in a similar way on the PG27UCDM.

We will provide measurements and data below based on forcing the DV modes on but for standard HDR10 input signals from a PC, to see if they offer anything above and beyond the normal HDR10 modes perhaps for PC usage.

Unfortunately at this time there isn’t a practical way to measure the actual performance of the Dolby Vision mode PQ EOTF tracking for actual Dolby Vision content. We originally expected to just need an external pattern generator, as you cannot use the built in generator that comes with Calman Ultimate as that only works with HDR10. We’ve done this in the past with DV-capable TV’s, with the pattern being “injected” over HDMI to the screen. However, the DV-capable monitors we’ve tested so far (i.e. this model and the Dell AW3225QF – since DV was not available at the time we tested the Asus PG32UCDM) seem to have challenges with the support for the DV tunnelling required to measure or calibrate in DV mode on PC monitors. These external pattern generators and software (including alternative professional packages beyond Calman) work fine on TV’s that support DV, but there seems to be added challenges with monitors. This is probably related to that lack of license agreement between Microsoft and Dolby.

For now, we can accurately measure the colour temp, luminance and colour accuracy of DV modes but when actual DV content is input to the screen, we do not have a way to measure the EOTF accuracy. We can only do this when HDR10 inputs are sent and you force DV mode on.

HDR Testing

PQ EOTF Tracking and Greyscale

Click between each tab to see results and analysis for each of the HDR modes

First the easy part of the comparison of all these HDR modes – they all have basically the same colour temp and white point, all being around 2 – 3% too warm for white, and around 4 – 5% too warm for the greyscale on average. The only mode which is a little worse is when you enable the ‘Dynamic Brightness Boost’ (D.B.B.) function, only available within the Console mode. That seems to skew the colour temp and white point a little further and is a bit warmer.

Where all these modes are different is in their PQ EOTF tracking, shown on the graph on the right hand side of each data table, here all measured based on an industry standard 10% APL window area test pattern.

For the various HDR10 modes, the DisplayHDR 400 True Black (herein referred to as ‘TB400’) has the most accurate EOTF tracking, which is a familiar situation for modern OLED screens and something we’ve explored in detail in the past. However, without wanting to pre-empt some of the results later, this mode cannot reach very high when it comes to peak brightness, again a familiar trade-off for the accurate EOTF tracking that we’ve seen on other screens. The 3 other HDR10 modes can reach a much higher peak luminance (more on that in a moment) but have different approaches to their EOTF tracking.

Have a look at the ‘EOTF comparison’ for HDR10 modes above where you can see the behaviour. Gaming HDR and Cinema HDR are very similar, with the only difference really being a slightly earlier roll-off point where the yellow target line on the graph levels out to flat. You can see the Gaming mode rolls off in its brightness a little sooner than the Cinema mode. Both these modes show a brighter-than-intended performance for the dark to mid grey shades where the grey line representing the monitor measurements is quite a lot higher than the yellow target line. This causes those shades to look brighter than they should be, elevating some dark to mid grey shades although not really impacting the visibility of the darkest shades near black. quite unusually this then drops back down to the target yellow line for grey shades of 50+, so those lighter grey shades are not as elevated.

Interestingly the Console HDR mode behaves differently to Gaming and Cinema modes and has very good EOTF tracking at this 10% APL measurement. We will need to consider other APL % to provide a fuller picture of brightness accuracy and actual real-world brightness further. If you enable the D.B.B. function when using the Console mode, it makes it behave very similarly to the Gaming and Cinema modes, raising the brightness of dark to mid grey shades.

Forcing the screen to use the Dolby Vision format with a normal HDR10 input from a PC we can also consider how those modes handle the EOTF tracking. It’s best again to look at the ‘DV comparison’ tab and you can see here that all 3 modes are very similar overall. The DV Bright mode follows the target PQ EOTF most accurately. DV Dark mode is slightly darker than the target line for mid to light grey shades, and DV Gaming slightly increases the brightness for dark grey shades near black. These are all very minor differences really.

Colour Accuracy

Click between each tab to see results and analysis for each of the HDR modes

All the HDR10 modes showed very similar colour gamut coverage (around 80% Rec.2020) and colour accuracy (rated very good) as you can see from the graphs above. There’s no real difference in these areas between any of the available modes. Enabling D.B.B. in the Console mode doesn’t really impact the colour accuracy at all for that mode.

The Dolby Vision modes are all very similar to one another so we’ve only included one for ease of reference. These DV modes have a slightly narrower colour space, covering ~74% of the Rec.2020 gamut in these modes, instead of ~80% in the HDR10 modes, leading to slightly less saturated colours and slightly worse colour accuracy for those colours as a result, but still very good overall.

HDR Brightness

Peak White Luminance

The common peak white luminance measurements are included here. As is usual for these OLED monitors the DisplayHDR mode (akin to a True Black 400 mode) is capped at a low brightness, reaching only 462 nits maximum in our measurements. The HDR10 Gaming and Cinema modes are basically identical, reaching 938 nits for the smallest APL % highlights. The HDR10 Console mode stretches a little higher still at 1012 nits, meeting the advertised spec of 1000 nits for the QD-OLED panel. If you enable the Dynamic Brightness Boost (D.B.B.) function in that mode, it makes it behave like the Gaming and Cinema modes instead.

All 3 Dolby Vision modes, when inputting an HDR10 source from a PC, behave very much like the True Black 400 mode, with a capped peak brightness of ~456 nits maximum, even for the smallest APL. We expected the ‘DV Bright’ mode to reach higher, and behave more like the HDR10 Gaming/Cinema/Console modes, but it didn’t, it was capped like the other two DV modes. We confirmed with Asus that this is deliberate behaviour for the DV modes as they need to meet the DV specification apparently, and seems like it’s a limitation of the DV spec rather than a monitor capability issue.

Keep in mind that these peak white luminance measurements only tell one part of the story when it comes to HDR brightness. We need to consider other areas as well…

Luminance Accuracy

To consider the “luminance accuracy” further of the HDR modes we need to consider the EOTF and luminance performance at a range of different APL’s. Our recent investigation of OLED HDR brightness has revealed that we can’t just rely on a single 10% APL measurement any more. If you’re unfamiliar with the testing and data in this section, you can expand the section below for more information.

Measuring the luminance accuracy reaffirms the observations we’d made earlier when looking only at the standard 10% APL measurements. In the HDR10 modes the True Black 400 mode provides the most accurate EOTF tracking at all APL window sizes, with the grey measurement line very closely tracking the yellow target line. As the APL increases, the roll-off point shifts a little to help preserve tonal values, as overall the screen can’t reach as bright in this mode. That’s normal and acceptable behaviour and it’s not too drastic here. The issue of course with this mode is that peak brightness is very limited, at around 462 nits peak brightness.

The HDR10 ‘Gaming’ and ‘Cinema’ HDR modes behave similarly to one another. These modes reach a higher peak luminance around 938 nits, but have a higher brightness than intended for dark to mid grey shades in some situations. This leads to some raising of darker grey shades. It’s mostly apparent for the smaller APL areas less than 25% but still evident for larger APL scenes to a degree. The grey measurement line is higher than the yellow target line on the graphs as you can see. As the APL increases the lines converge a little more closely but mid to light grey shades start to look darker than they should be, where the measurement line dips below the target line in the middle of the graph. You can see this happens for the 50% and 100% APL measurements for instance.

The ‘Console HDR’ mode behaves more like a traditional ‘Peak 1000’ mode we’ve seen on many QD-OLED monitors in the past. It reaches the highest peak white luminance (1012 nits) and it’s EOTF tracking looks accurate for a 10% APL window test. However, the screen is darker than intended for mid to light grey shades where the line dips considerably below the target considerably for larger APL. This is a bit more drastic than in the ‘Gaming’ and ‘Cinema’ modes. This is typical behaviour for these ‘Peak 1000’ modes and it leads to an overall darker HDR experience in real usage. We will explore the HDR brightness a bit more in a moment.

If you enable the ‘Dynamic Brightness Boost’ (D.B.B.) setting in the HDR10 Console mode, it makes it behave like the Cinema and Gaming modes. This seems a bit pointless given those other modes are available too unless you specifically wanted to configure this mode manually in other areas and use it for consoles, while keeping the Gaming and Cinema modes for other devices/inputs.

The Dolby Vision modes are all capped at the moment to around 455 nits and their EOTF tracking ends up being very similar to the True Black 400 mode as a result. Nice and accurate at all APL, with some subtle roll-off as the APL gets larger. But these modes have restrictive peak brightness unfortunately.

Greyscale Luminance

If we plot the average greyscale brightness for mid to light tones you can compare the different modes as shown above. This is a reflection of real-world HDR brightness in real content, so is a useful step beyond the standard ‘peak white luminance’ measurements we provided earlier.

While the TB400 and Dolby Vision modes showed the lowest peak brightness capability (around 450 – 460 nits), they are generally a bit brighter in real content and for the greyscale than the other modes, especially for the larger APL scenes. This is a pattern we’ve seen before on QD-OLED monitors with TB400 and Peak 1000 modes.

The HDR10 Console mode might reach the highest peak white luminance (1012 nits) but is actually the darkest in real content due to the significant drop off in the EOTF tracking for mid and light grey shades, which make up a big part of brighter HDR scenes. That’s a common behaviour for ‘Peak 1000’ type modes at the moment as well.

The HDR10 Gaming, Cinema and Console (D.B.B. enabled) modes are a little brighter because of their raised EOTF tracking, although that largely impacts darker scenes and darker grey shades making those a bit brighter than intended, but still with some drop off in mid/light shades still as we covered earlier. We’ve seen some other screens push the brightness higher still to protect more against that drop off, but that’s at the cost of accuracy so there’s always a trade off.

The HDR10 Gaming and Cinema modes could be tweaked a little further to increase overall HDR brightness, or perhaps the ‘dynamic brightness boost’ option could be adjusted to be a bit brighter like they did for the 32″ PG32UCDM. That provided an option for a brighter HDR experience, albeit at the cost of accuracy and some crushing of brighter details. Ideally of course there would be a mode that delivers the full peak brightness capability AND offers accurate EOTF tracking at all APL. So far no one has achieved that.

Conclusion

The PG27UCDM is yet another really impressive OLED monitor from Asus, offering just about all the specs, features and extras you could want. It was great to see 4K resolution finally available from a 27″ sized screen, offering a very impressive picture quality, sharpness and pixel density. Text clarity and detail were excellent, and this higher PPI has helped basically eliminate any lingering problems with text visually on the QD-OLED panels. Combined with the familiar semi-glossy screen coating it provides a sharp and crisp image for work, content creation, multimedia and gaming.

We already knew what to expect for gaming from a 240Hz OLED panel and this screen offers the usual excellent response times and motion clarity as well as a super-low input lag. It’s missing the ‘dual-mode’ functionality and boosted refresh rate that their 32″ 4K PG32UCDP offers which might be a shame to some people, but right now there’s no 27″ 4K OLED monitors that offer that. The added ELMB / BFI function will be useful to some people and worked well for improving motion clarity in some situations. We’d like to see the operation of this mode improved, along with the brightness if possible. The updated Anti Flicker modes will hopefully be useful for VRR gaming, although this is hard to quantify as there’s so many variables that can impact flicker in these situations. A focus from Asus on improving the situation and offering settings that allow you to tweak things is very welcome though. Console support was excellent, again nicely making use of the 4K resolution, OLED panel capabilities and included HDMI 2.1 connections.

Speaking of connections, a lot of people will be pleased to see a proper DisplayPort 2.1 connection included with UHBR20 bandwidth, ready to accommodate future graphics cards and offer an uncompressed video signal. With this connection starting to become a bit more common, it’s good to see Asus develop around that for this new screen. The inclusion of USB-C, data ports, a KVM switch function and PiP/PbP modes will be useful to some users too and it’s nice to see them all included on what is primarily a gaming screen.

Default setup was very good, with high levels of accuracy and flexible and useable emulation modes for things like SDR/sRGB work. The updated and improved OLED Care Pro features help give some additional reassurance around image retention and burn-in and we liked the new Neo Proximity Sensor and how that is configured and used. The fan-less design is always welcome too, along with a decent 3 year warranty with burn-in cover.

The OLED panel provides all the usual benefit when it comes to HDR with per pixel level dimming and true blacks. Being a QD-OLED panel you need to be mindful of your lighting positioning and levels to avoid raised blacks from this technology. There’s a very wide range of HDR modes, configurations and settings available and it was great to see support for HDR10 and DV content. We’d have liked an option to have an even brighter HDR mode when using the ‘Dynamic Brightness Boost’ function, as even with that enabled the HDR10 modes can often look darker than the True Black 400 modes, despite being able to reach a higher peak brightness. A brighter DV mode would also be welcome although this might be restricted due to Dolby Vision standards it seems.

The PG27UCDM will be available for pre-order from January 21st in the United States of America from various retailers including Newegg (affiliate link). It will also be showcased at CES next week and we will be on hand to bring you all the latest news from the Asus booth and product ranges.

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