AOC CU34G2X

Interlace pattern artifacts

On some monitors, particularly but not exclusively those with high refresh rates, interlace patterns can be seen during certain transitions. We refer to these as ‘interlace pattern artifacts’ but some users refer to them as ‘inversion artifacts’ and others as ‘scan lines’. They may appear as an interference pattern, mesh or interlaced lines which break up a given shade into a darker and lighter version of what is intended. They often catch the eye due to their dynamic nature, on models where they manifest themselves in this way. Alternatively, static interlace patterns may be seen with some shades appearing as faint horizontal or vertical bands of a slightly lighter and slightly darker version of the intended shade.

We observed dynamic interlace pattern artifacts in the form of a polygonal mesh when observing movement with some medium to light shades (smoke, clouds and suchlike). This pattern was extremely faint and difficult to notice for the most part, although it became somewhat more noticeable (but not extreme) during frame rate drops below 100fps with Adaptive-Sync active. We also observed some static interlace pattern artifacts. These were visible mainly but not exclusively for some medium to light grey and blues plus some red and orange shades. They were faintest at 60Hz and became more visible at higher refresh rates. Even at 144Hz they remained reasonably faint, so most users would find them fine or simply not notice them during normal use. Sensitive users might notice them and potentially find them bothersome, however.

Responsiveness

Input lag

A small utility called SMTT 2.0 was used alongside a sensitive camera to analyse the latency of the CU34G2X, with over 30 repeat readings taken to help maximise accuracy. Using this method, we calculated 5.28ms (around 3/4 of frame at 144Hz) of input lag. There was no measurable difference at 144Hz with ‘Low Input Lag’ enabled in the OSD vs. ‘Adaptive-Sync’ set to ‘On’ in the OSD and enabled in the graphics driver. We recorded a similar value at 60Hz, provided ‘Low Input Lag’ was enabled in the OSD and Adaptive-Sync was disabled. At 60Hz having ‘Adaptive-Sync’ enabled appeared to add an additional frame of delay compared to ‘Low Input Lag’ being enabled – ~16ms extra (~21ms total).

Note that the input lag measured here is influenced by both the element you ‘see’ (pixel responsiveness) and the element you ‘feel’ (signal delay). It indicates a reasonably low signal delay which most users should be comfortable with. Unfortunately, we don’t have the means to accurately measure input lag with Adaptive-Sync active in a variable refresh rate environment or with HDR active in an HDR environment.

Perceived blur (pursuit photography)

We’ve got an article on monitor responsiveness which explores some key aspects of the topic. A principle idea explored here is perceived blur, which is contributed to by both the pixel responsiveness of the monitor and the movement of your eyes as you track motion on the screen. Both factors are important, although it’s actually your own eye movement which creates most perceived blur on modern monitors. In the article we also cover a photography technique called ‘pursuit photography’. This uses a moving camera to capture motion on a screen in a way that reflects both elements of perceived blur, rather than simply reflecting pixel responsiveness.

The images below are pursuit photographs taken using the UFO Motion Test for ghosting, with the UFO moving across the screen from left to right at a frame rate matching the refresh rate of the display. The test is set to run at its default speed of 960 pixels per second, which is a practical speed for such photographs whilst also highlighting key weaknesses. The monitor was tested at 60Hz (directly below), 100Hz and 144Hz with all ‘Overdrive’ options analysed; ‘Off’, ‘Weak’, ‘Medium’ and ‘Strong’. Although not documented here, 120Hz behaved some way between the tested refresh rates (100Hz and 144Hz), as you might expect. All rows of the UFO Motion Test were used to help broaden the shades (grey levels) tested. The final columns show some reference screens for comparison, both set to what we consider their optimal pixel response time settings. The first reference screen is the AOC C24G1, an interesting point of comparison as we consider this to be a pretty well-tuned VA model in terms of pixel overdrive. The second reference screen is the ViewSonic XG240R, a fast and well-tuned TN model (particularly at high refresh rates) that shows how things look where pixel responsiveness isn’t really a limiting factor. Note that the saturation and brightness of the screen and the way the camera captured things caused the segments of the UFO to appear a bit more blended on the CU34G2X than they do in reality. The segmentation is a bit more distinct in reality, similar to the respective reference shots.



At 60Hz, shown above, the UFO appears softly focused and relatively broad. This look to the object itself reflects a significant amount of perceived blur due to eye movement and is shared with the reference screens. Behind the UFOs you can see varying degrees of trailing, caused by weaknesses in pixel responsiveness. Moving up from ‘Off’ to ‘Weak’ and then ‘Medium’ offers slight incremental improvements to pixel responsiveness. The boldest trailing is observed for the dark background (top row), with the medium background (middle row) showing a reduction and the light background (bottom row) a further reduction. Using the ‘Medium’ setting, you can see a little overshoot (inverse ghosting) introduced for the light background. More specifically a little ‘halo trailing’ that’s brighter than the object or background colour. There is a bit more overshoot for the C24G1 reference shots but less conventional trailing. The ‘Strong’ overdrive setting introduces extreme overshoot, bright and colourful trailing that’s extremely eye-catching both in the images and in practice. We consider ‘Medium’ to be the optimal setting at 60Hz. The following image set shows how things look with the refresh rate bumped up to 100Hz.



At 100Hz, shown above, the UFO now appears somewhat narrower and more sharply focused. This reflects a significant decrease in perceived blur due to eye movement. You can again see varying degrees of trailing behind the object. There was again an incremental improvement going up from ‘Off’ to ‘Weak and then ‘Medium’. The trailing behind was more extended and somewhat bolder than at 60Hz, reflecting the more stringent pixel response requirements of the increased refresh rate. The ‘Strong’ setting again introduced extreme overshoot, particularly for the medium background. We again consider the ‘Medium’ setting optimal at 100Hz. The trailing is more distinct than on the C24G1 reference and certainly compared to the snappy XG240R reference at this refresh rate. The image below shows what things look like with a further bump up in refresh rate to 144Hz.



At 144Hz, above, the UFO appears somewhat narrower with sharper internal detailing. This reflects a further decrease in perceived blur due to eye movement. There was again varying degrees of trailing behind the object, due to weaknesses in pixel responsiveness. With another step up in refresh rate, the pixel response requirements for optimal performance increase further. The trailing is therefore slightly more extended in places compared to at 100Hz, but this was marginal. The weaknesses were already exposed quite readily by 100Hz. The ‘Strong’ setting again introduces obvious overshoot, especially for the medium background. We consider the ‘Medium’ setting optimal again due to a slight reduction in trailing compared to the ‘Weak’ setting without a noticeable negative impact. This is reflected by broader testing. Comparing to the references, the C24G1 shows somewhat less bold trailing behind the cockpit (yellow area) of the UFO for the dark background and less trailing throughout for the medium background. The light background is actually a bit cleaner on the CU34. The XG240R is a superstar at 144Hz, very well-optimised with no obvious weaknesses apparent on this test.

As well as increasing refresh rate to minimise perceived blur due to eye movement, the monitor offers an alternative with its ‘MBR’ (Motion Blur Reduction) feature. This is a strobe backlight setting that causes the backlight to pulse at a frequency matching the refresh rate of the display – either 100Hz, 120Hz or 144Hz. Adaptive-Sync must be disabled, otherwise MBR and associated settings are inaccessible. By its very nature, this mode causes the backlight to flicker at a rate matching the refresh rate of the display – individual sensitivity to this flickering varies. Some users may notice accelerated eye fatigue when using this setting even if they aren’t actively noticing any flickering. The pursuit photographs below were taken with the monitor set to 144Hz with MBR active and set to various values. Under MBR, the brightness slider is greyed out and replaced by the ability to set MBR between ‘1’ and ‘20’. This adjusts the ‘Pulse Width’, with a higher number decreasing the length of time for the on periods of the backlight pulses. This decreases brightness whilst potentially improving motion clarity. We also test a new overdrive setting called ‘Boost’ that’s available with Adaptive-Sync disabled that sets the monitor to ‘MBR = 20’ with different tuning to the other overdrive settings.



With MBR active you can see that the image appears more sharply focused compared to with the setting deactivated, reflecting a significant decrease in perceived blur due to eye movement. This is most noticeable at ‘MBR = 20’ or with ‘Overdrive = Boost’ (same MBR level), which corresponds with the dimmest setting with highest potential motion clarity. We’d again stress that the camera made the segments appear a bit less distinct than they appeared to the eye, at ‘MBR = 10’ and above. You can see that the trailing is now fragmented due to the strobe nature of the backlight. These repetitions are due primarily to the pixel responses not keeping up with the rigorous demands of the refresh cycle. The all-encompassing term ‘strobe crosstalk’ is used to describe this fragmented trailing around the object. The fragmentation of the trailing is clearest at increased MBR levels. Using the ‘Strong’ setting there is very strong overshoot for the medium background and a smaller amount for the light background.

The ‘Boost’ setting maintains similar overshoot levels to ‘Strong’ for the light background. For the dark and medium backgrounds ‘Boost’ sits some way between ‘Medium’ and ‘Strong’, reducing the boldness of the fragmented trailing without introducing overshoot. We consider the ‘Boost’ setting optimal for this reason, but the imperfections (strobe crosstalk) are still rather eye-catching and impair motion clarity a lot more than in the reference shots. The images below show the monitor running with this ‘Boost’ setting but set to 100Hz and 120Hz, allowing comparison with the 144Hz MBR performance. The pixel overdrive settings and relative effect of the MBR level worked in much the same way at reduced frame rate, so we’re keeping the comparison a bit simpler here.



The internal detailing is somewhat reduced at a respective decrease in refresh rate. But even at 100Hz, there’s a certain level of focus and narrowness to the object that simply isn’t there with MBR deactivated. Even in an apples to oranges comparison with 144Hz. This is due to a significant decrease in perceived blur due to eye movement when using MBR, even when compared with a higher refresh rate and the setting deactivated. The strobe crosstalk we mentioned earlier – imperfections you see around the main object – is visible in much the same way. There are multiple repetitions and particularly for the dark background many of these repetitions are particularly bold and distinct. It’s worth noting not all areas of the screen refresh simultaneously, so the appearance of strobe crosstalk can differ depending on how high up or low down on the screen the movement is being observed. This is demonstrated in the image below, with the monitor set to our preferred ‘Boost’ setting at 144Hz.



You can see rather strong strobe crosstalk throughout the screen. Further up you can see it in front of the object as well as behind. A bit lower down (just above centre) it only appears behind. Centrally the strobe crosstalk appears only behind the object, but the initial trail in particular appears bolder. A bit further down the screen the initial trail becomes so bold it’s essentially a duplication of the main object. This strobe crosstalk didn’t make the MBR setting useless by any means, but it did impact its motion clarity. We explore this subjectively with some in-game testing shortly.

Responsiveness in games and movies

On Battlefield V, at frame rates keeping pace with the refresh rate, the monitor offered a reasonably low level of perceived blur. Most of this perceived blur was linked to eye movement and the 144Hz refresh rate. With the monitor pumping out ~2.4 times as much visual information ever second as a 60Hz monitor (or this running at 60Hz), there was a significant reduction in eye movement and hence a decrease in perceived blur. In addition, the high refresh rate and frame rate combination greatly improved the ‘connected feel’. This describes the precision and fluidity during interactions with your character and the game world. The low input lag helped in this respect, too. There were some weaknesses in pixel responsiveness which added to overall perceived blur, however. Such weaknesses are common on VA models, although there’s still quite a gap between the fastest and slowest VA performers. We’d put this one somewhere in the middle in that respect, with more pronounced weaknesses in pixel responses compared to something like the Acer X35 but a significant improvement over some models, like the Acer Z35.

Where lighter and medium shades were involved in the transitions, more common during brightly lit daylight scenes on BFV for example, the weaknesses were relatively minor. Some ‘light powdery’ trailing in places, adding a bit of perceived blur. Where darker or medium-dark shades were added to the equation, some more pronounced weaknesses were observed. This included ‘heavy powdery’ trailing and some with a ‘smeary’ appearance – a bolder and more extended form of trailing which significantly increases perceives blur for affected transitions. This was clearest where very dark shades moved against lighter backgrounds, such as a dark tree trunk against a dusky sky. Or bright objects such as white text moved against medium to dark shades such as earth or sand. We observed some ‘break-up’ trailing as well, whereby some of the hues contained in the object or background appeared to leach out in a more obvious way. Purples and blues for example, appearing to flow out of some dark objects as if you’re wetting a page with water soluble ink on it. These weaknesses certainly weren’t as pronounced as we’ve seen on some VA models and overall performance will be just fine for some users, but we still found these weaknesses quite eye-catching. There were traces of overshoot in places as well, but this was very light and easy to ignore in comparison. The section of video review below highlights the strengths and weaknesses of the pixel response performance.

We made similar observations on Shadow of the Tomb Raider. The weaknesses described previously were brought out here because of how common darker shades were. Lots of dimly lit locations, inviting the ‘smeary’ trailing and ‘heavy powdery’ trailing. There was no extensively ‘smoke-like’ trailing, which you’d get from some of the slowest VA performers. Sometimes the weaknesses in pixel responses manifested themselves as a sort of ‘flickering’ effect, very commonly observed on VA models. Where there were fine alternations between bright and dark shades, such as thatched roofing, the brighter shades were dimmed during movement due to being blended with the darker shades. There was no real overshoot to speak of using our preferred ‘Medium’ overdrive setting. To add to our comparisons with other models made previously, the weaknesses in pixel responsiveness were somewhat more pronounced than on the AOC C24G1 using its ‘Medium’ overdrive setting. And unlike on that model, the ‘Strong’ setting on this one is useless due to extreme overshoot levels. But we wouldn’t say it’s a million miles away. For gamers who enjoy playing titles like this, we feel they’ll generally be able to enjoy some benefits from the 144Hz refresh rate where frame rate permits (enhanced ‘connected feel’ and reduced perceived blur). And they may not find the standout weaknesses too much of a distraction – but it’s ultimately very subjective.

We also observed video content at a range of frame rates, including 24 – 30fps Netflix content and 60fps YouTube content. For the 24 – 30fps content we didn’t observe any distinct weaknesses, perhaps a small amount of ‘powdery’ trailing for some transitions with dark shades but nothing that stood out. For the higher frame rate content these weaknesses were more apparent, although not as pronounced as during our high frame rate gameplay. The pixel response requirements are significantly lower at such reduced frame rates and you don’t need to worry about losing a competitive edge – because you’re sitting there passively watching the action. Despite still being noticeable to us in places, the weaknesses didn’t really detract too much from the video viewing experience even at 60fps.

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FreeSync – the technology and activating it

AMD FreeSync is a variable refresh rate technology, an AMD-specific alternative to Nvidia G-SYNC. Where possible, the monitor dynamically adjusts its refresh rate so that it matches the frame rate being outputted by the GPU. Both our responsiveness article and the G-SYNC article linked to explore the importance of these two elements being synchronised. At a basic level, a mismatch between the frame rate and refresh rate can cause stuttering (VSync on) or tearing and juddering (VSync off). FreeSync also boasts reduced latency compared to running with VSync enabled, in the variable frame rate environment in which it operates.

FreeSync requires a compatible AMD GPU such as the Radeon RX 580 used in our test system. There is a list of GPUs which support the technology here, with the expectation that future AMD GPUs will support the feature too. The monitor itself must support ‘VESA Adaptive-Sync’ for at least one of its display connectors, as this is the protocol that FreeSync uses. The CU34G2X supports FreeSync via DP and HDMI on compatible GPUs and systems. Note that HDR can be activated (at the same time as FreeSync) on GPUs and systems with DP 1.4 or HDMI 2.0. With the CU34G2X you also need to make sure ‘Adaptive-Sync’ is set to ‘On’ in the ‘Game Setting’ section of the OSD. On the GPU driver side recent AMD drivers make activation of the technology very simple and something that usually occurs automatically. You should ensure the GPU driver is setup correctly to use FreeSync, so open ‘AMD Radeon Software’, click ‘Settings’ (cog icon towards top right) and click on ‘Display’. You should then ensure that the first slider, ‘Radeon FreeSync’ is set to ‘Enabled’ as shown below.



The AOC supports a variable refresh rate range of 48 – 144Hz. That means that if the game is running between 48fps and 144fps, the monitor will adjust its refresh rate to match. When the frame rate rises above 144fps, the monitor will stay at 144Hz and the GPU will respect your selection of ‘VSync on’ or ‘VSync off’ in the graphics driver. With ‘VSync on’ the frame rate will not be allowed to rise above 144fps, at which point VSync activates and imposes the usual associated latency penalty. With ‘VSync off’ the frame rate is free to climb as high as the GPU will output (potentially >144fps). AMD LFC (Low Framerate Compensation) is also supported by this model, which means that the refresh rate will stick to multiples of the frame rate where it falls below the 48Hz (48fps) floor of operation for FreeSync. If a game ran at 36fps, for example, the refresh rate would be 72Hz to help keep tearing and stuttering at bay. This feature is used regardless of VSync setting, so it’s only above the ceiling of operation where the VSync setting makes a difference.

To configure VSync, open ‘AMD Radeon Software’. Click ‘Settings’ (cog icon towards top right) and click ‘Graphics’. The setting is listed as ‘Wait for Vertical Refresh’. This configures it globally, but if you wish to configure it for individual games click ‘Game Graphics’ towards the top right. The default is ‘Off, unless application specifies’ which means that VSync will only be active if you enable it within the game itself, if there is such an option. Such an option does usually exist – it may be called ‘sync every frame’ or something along those lines rather than simply ‘VSync’. Most users will probably wish to enable VSync when using FreeSync to ensure that they don’t get any tearing. You’d therefore select either the third or fourth option in the list, shown in the image below. Above this dropdown list there’s a toggle for ‘Radeon Enhanced Sync’. This is an alternative to VSync which allows the frame rate to rise above the refresh rate (no VSync latency penalty) whilst potentially keeping the experience free from tearing or juddering. This requires that the frame rate comfortably exceeds the refresh rate, not just peaks slightly above it. We won’t be going into this in detail as it’s a GPU feature rather than a monitor feature.



Some users prefer to leave VSync enabled but use a frame rate limiter set a few frames below the maximum supported (e.g. 141fps) instead, avoiding any VSync latency penalty at frame rates near the ceiling of operation or tearing from frame rates rising above the refresh rate. If you enable ‘Frame Counter’ in the ‘Game Setting’ section of the OSD, this will reflect the frame rate when the monitor is within its variable refresh rate range and Adaptive-Sync is doing its thing. The final point to note is that FreeSync only removes stuttering or juddering related to mismatches between frame rate and refresh rate. It can’t compensate for other interruptions to smooth game play, for example network latency or insufficient system memory. Some game engines will also show stuttering (or ‘hitching’) for various other reasons which won’t be eliminated by the technology.

FreeSync – the experience

We ran a range of game titles with FreeSync enabled on the monitor and as usual found it worked in much the same way across these titles. Any issues identified on one specific title would suggest a game or GPU driver issue rather than a monitor issue. We’ll therefore simply focus on a single title for this section; Battlefield V. With excellent flexibility with its graphics settings and scenes of varying intensity, it allows the full refresh rate range of the monitor to be tested under FreeSync. The lowly Radeon RX 580 used in our test system is no powerhouse, so maintaining a solid 144fps was difficult even with significant graphics settings sacrifices. Without a variable refresh rate technology such as FreeSync, even slight dips in frame rate would cause obvious tearing (VSync disabled) or stuttering (VSync enabled). Obvious to us at least, as users sensitive to tearing and stuttering. Having such nuisances removed was a very nice bonus.

With more significant dips in frame rate, the technology continued to work to get rid of tearing and stuttering. There was a drop off in ‘connected feel’ and an increase in perceived blur as frame rate was reduced. FreeSync doesn’t change the fact that lower frame rates are still lower frame rates – it just helps remove tearing and stuttering from mismatches between frame and refresh rate. The technology worked all the way down to 48Hz (48fps) and even at such low refresh rates there was no obvious overshoot introduced. Unlike monitors with G-SYNC modules, Adaptive-Sync models like this typically lack variable overdrive and are only really tuned for their native refresh rate (144Hz in this case). As refresh rate reduces, occurring alongside frame rate dips with Adaptive-Sync active, the pixel overdrive should ideally be re-tuned to avoid the introduction of increasingly obvious overshoot. Whilst there was some extra overshoot introduced using our preferred ‘Medium’ pixel overdrive setting, it was not substantial and wasn’t something most users will find bothersome or necessarily notice at all.

Beneath 48fps, the monitor employed LFC and stuck with a multiple of the frame rate with its refresh rate. Keeping tearing and stuttering at bay. When crossing the LFC boundary, we observed momentary flickering – something we very commonly observe on FreeSync models. We noticed more intense and actually quite bothersome flickering during certain frame rate fluctuations below the LFC boundary, however. Fluctuations between 20 – 40fps, for example, caused very obvious flickering which we found quite distracting. We observed some mild flickering at times outside of the LFC window (>48fps) as well. This generally occurred during significant fluctuations in frame rate, such as a sudden momentary drop of 40-50fps followed by an increase. We commonly observe flickering on VA models under such conditions as they’re sensitive to the sudden voltage changes that occur in such scenarios. Sometimes heavy fluctuations in frame rate with a variable refresh rate technology active can cause slight flickering with models using other panel types as well. Unlike the flickering observed in the LFC window (<48fps), we didn’t find this bothersome or distracting during gameplay - but some users might.

Nvidia Adaptive-Sync (‘G-SYNC Compatible’)

As noted earlier, AMD FreeSync makes use of Adaptive-Sync technology on a compatible monitor. As of driver version 417.71, users with Nvidia GPUs (GTX 10 series and newer) and Windows 10 can also make use of this Variable Refresh Rate (VRR) technology. When a monitor is used in this way, it is something which Nvidia refers to as ‘G-SYNC Compatible’. Some models are specifically validated as G-SYNC compatible, which means they have been specifically tested by Nvidia and pass specific quality checks such as the inclusion of effective variable overdrive. The make use of the technology, you need to connect the monitor up via DisplayPort and make sure ‘Adaptive-Sync’ is set to ‘On’ in the ‘Game Setting’ section of the OSD. When you open up Nvidia Control Panel, you should then see ‘Set up G-SYNC’ listed in the ‘Display’ section. Ensure the ‘Enable G-SYNC, G-SYNC Compatible’ checkbox as well as ‘Enable settings for the selected display model’ is enabled as shown below. Press OK – the monitor should briefly flick off then on again and the technology should be active.



You will also see in the image above that it states: “Selected Display is not validated as G-SYNC Compatible.” This means Nvidia hasn’t specifically tested and validated the display, not that it doesn’t work. The technology did indeed work, largely mirroring the FreeSync experience including allowing HDR to be used simultaneously. At least, the overall experience was similar at higher frame rates and refresh rates. The floor of operation was shifted up to 70Hz (70 – 144Hz) instead of 48Hz. When the frame rate fell below 70fps, an LFC-like frame to refresh multiplication technology was used. Unfortunately, when the monitor passes the LFC boundary or sits below this, it frequently caused the screen to go blank for a split second and then turn back on. This will be fine if you’re always well clear of the boundary, but unexpected dips down to 70fps or below are sometimes difficult to avoid. Some game menu systems will cause such dips, even if the game itself can be run at much higher frame rates. According to our research and experience with other models, this issue may not exist on newer GPU generations such as the RTX 20 and RTX 30 Series.

Our suggestions regarding use of VSync also apply, but obviously you’re using Nvidia Control Panel rather than Radeon Settings to control this. The setting is found in ‘Manage 3D settings’ under ‘Vertical sync’, where the final option (‘Fast’) is equivalent to AMD’s ‘Enhanced Sync’ setting. You’ll also notice ‘G-SYNC Compatible’ listed under ‘Monitor Technology’ in this section, as shown below. Make sure this is selected (it should be if you’ve set everything up correctly in ‘Set up G-SYNC’).



Finally, note again that you can enable ‘Frame Counter’ in the ‘Game Setting’ section of the OSD. This will reflect the frame rate when the monitor is within its variable refresh rate range and Adaptive-Sync is doing its thing.

MBR (Motion Blur Reduction)

Earlier on we introduced the ‘MBR (Motion Blur Reduction)’ feature, including its principles of operation and how it performs using specific tests. When using MBR or any strobe backlight feature, it’s essential that your frame rate exactly lines up with the refresh rate of the display. If that isn’t the case, you’re left with extremely obvious stuttering or juddering, which stands out because there’s very little perceived blur due to eye movement to mask it. You can’t use Adaptive-Sync at the same time as MBR. We tested a range of games whilst using the feature but for simplicity will simply focus on Battlefield V, running solidly at 144fps. The monitor was set to 144Hz using the ‘Boost’ setting, which as we explored earlier we consider to be optimal in terms of motion clarity. Some of the observations made below apply to other overdrive settings and refresh rates, however.

There was certainly a reduction in perceived blur overall compared to having the feature disabled. The clarity of the main object was demonstrated using ‘Test UFO’ earlier and is also reflected during gameplay. Rapid turns resulted in superior detail levels being retained, potentially giving a competitive edge and making it easier to engage and track enemies. This was not the ‘cleanest’ strobe crosstalk implementation, however. There was a fair degree of strobe crosstalk and general pixel response time weaknesses evident throughout the screen. With repetitions of various objects, the environment enemies and anything else that might be moving in the scene. Quite a few of these repetitions were at least fainter than the actual object or element, but some were almost as bold. Particularly where darker shades were included or further down the screen where strobe crosstalk was very strong even for medium shades. The strobe crosstalk was detrimental to motion clarity and just looked a bit messy in places. Additional points to note include that the backlight flickers at a frequency matching the refresh rate of the display, which could bother sensitive users. We also observed some red and green flashes at times, especially when moving the eyes rapidly or observing thin white objects moving on the screen. This is something we commonly notice on wide gamut models with strobe backlight implementations. Coupled with the flickering, we found using MBR accelerated visual fatigue and preferred the normal flicker-free operation of the monitor. But sensitivity to flickering varies and some users may see some utility in this mode despite its drawbacks.

HDR (High Dynamic Range)

On an ideal monitor, HDR (High Dynamic Range) involves simultaneous output of very bright light shades and very deep dark shades. Additionally, the monitor must possess the ability to display an excellent range of shades between these extremes. From muted pastel shades to highly vivid saturated shades. Ideally the monitor would allow per-pixel illumination or failing that offer many dimming zones controlled with excellent precision. In other words, an FALD (Full Array Local Dimming) solution with a very high number of dimming zones which allows some areas of the image to remain very dim whilst others are very bright. Colour reproduction is also an important aspect of the HDR experience. The ultimate goal is support for a huge colour gamut, Rec. 2020, whilst a more achievable near-term goal is for a monitor to offer coverage of at least 90% DCI-P3 (Digital Cinema Initiatives standard colour space). Finally, HDR makes use of at least 10-bit precision per colour channel, so its desirable that the monitor supports at least 10-bits per subpixel.

Monitors most commonly support the HDR10 pipeline, the most ubiquitous HDR standard used in HDR games and movies. For most games and other full screen applications that support HDR, the AOC CU34G2X automatically switches into its HDR operating mode. As of the latest Windows 10 update, relevant HDR settings in Windows are found in ‘Windows HD Color settings’ which can be accessed via ‘Display settings’ (right click the desktop). Most game titles will activate HDR correctly when the appropriate in-game setting is selected. A minority of game titles that support HDR will only run in HDR if the setting is active in Windows as well. Specifically, the toggle which says ‘Play HDR games and apps’. If you want to view HDR movies on a compatible web browser, for example, you’d also need to activate the ‘Stream HDR Video’ setting. These settings are shown below. Also note that there’s a slider that allows you to adjust the overall balance of SDR content if HDR is active in Windows. This simply acts as a digital brightness slider, so you lose but never gain contrast by adjusting it. For regular SDR content, the image generally appeared bleached, unappealing and poorly balanced regardless of what this was set to. We’d recommend only activating HDR in Windows if you’re about to specifically use an HDR application that requires it, and have it deactivated when viewing normal SDR content on the monitor.

For this section we’ll focus on two titles; Battlefield V and Shadow of the Tomb Raider. These and similar titles are ones we’ve tested on a broad range of monitors under HDR and we know they offer a solid HDR experience on monitors with appropriate capability. Although this testing is focused on HDR PC gaming using DisplayPort and HDMI, the observations apply more broadly to other HDR content including HDR movies and running HDR on compatible games consoles. The experience described here is largely dictated and limited by the screen itself. The monitor has 4 different ‘HDR’ settings available under HDR in the ‘Luminance’ section of the OSD; ‘DisplayHDR’, ‘HDR Picture’, ‘HDR Movie’ and ‘HDR Game’. Image controls such as ‘Brightness’, ‘Contrast’, ‘Gamma’ and the ‘Color Setup’ menu are locked off under HDR. We’ll discuss the HDR modes shortly, but first it’s worth talking a bit about where the monitor sits in terms of its overall HDR capabilities and specification. The AOC CU34G2X does not meet the criteria for even the lowest level of VESA DisplayHDR certification. The HDR output of the monitor is therefore very rudimentary, although that’s not to say some users won’t enjoy some elements of the experience. We recorded a colour gamut of 88% DCI-P3 on the AOC. This is shown in the gamut representation below, where the red triangle shows the monitor’s colour gamut, the blue triangle shows DCI-P3 and green triangle sRGB for reference. Because DCI-P3 is the near-term standard game developers and HDR movie directors have in mind when creating HDR content, it makes sense to have good coverage of this colour space for HDR purposes.

Colour gamut 'Test Settings'