Acer XB253Q GP

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 faint vertical static interlace patterns, but at higher refresh rates in particular these were not too obvious. Even at ~60Hz and below they were faint enough to escape the notice of most users. The ‘Over Drive’ setting or Adaptive-Sync status didn’t affect these observations.

Responsiveness

Input lag

A sensitive camera and a utility called SMTT 2.0 was used alongside a sensitive camera to analyse the latency of the Acer XB253Q GP. Over 30 repeat readings were taken to help maximise accuracy. Using this method, we calculated 3.35ms (under ½ a frame at 144Hz) of input lag. At 60Hz we measured a slightly higher but still fairly low 4.50ms. These figures are influenced by both the element of input lag you ‘see’ (pixel responsiveness) and the element you ‘feel’ (signal delay). They indicate a low signal delay, especially at 144Hz, which even sensitive users shouldn’t find bothersome. Note that ‘Ultra-Low Latency’ was enabled during this testing – more specifically ‘Adaptive-Sync’ was enabled in the OSD, which forces this on and greys the option out. We have no way to accurately measure input lag with Adaptive-Sync active in a variable refresh rate environment or with HDR active in an HDR environment, however.

Perceived blur (pursuit photography)

Our article on responsiveness explored the key factors affecting monitor responsiveness. An important concept is explored here called ‘perceived blur’, which is contributed to not just by the pixel responses of the monitor, but also your eye movement as you track motion on the screen. This second factor usually dominates on modern monitors, although both are important. We also explore a photography technique that uses a moving rather than stationary camera to capture motion on a monitor in a way that reflects both elements of perceived blur; ‘pursuit photography’.

The images below are pursuit photographs taken using the UFO Motion Test for ghosting, with the test running at its default speed of 960 pixels per second. This is a good practical speed to take such photographs at, highlighting both elements of perceived blur nicely. The UFOs move across the screen from left to right at a frame rate matching the refresh rate of the display. All three rows of the test are analysed to show a range of pixel transitions. The monitor was tested at 60Hz (directly below), 120Hz and 144Hz using all available ‘Over Drive’ settings; ‘Off’, ‘Normal’ and ‘Extreme’. Where possible, reference shots are included in the final columns for comparison. These include the AOC 24G2(U), with its 23.8” Panda IPS-type panel and the ViewSonic XG240R with its very fast (and well-tuned for 144Hz) 24” TN panel. The references are set to what we consider the optimal pixel overdrive setting for a given refresh rate. Wavy patterns surrounding some UFOs in the background are slight image retention. This was only observed during this test and is something we’ve seen on various monitors before. It soon disappeared when using monitor normally.

Note that if ‘Adaptive-Sync’ is set to ‘On’ in the OSD, it greys out the ‘Over Drive’ setting. Confusingly, if the ‘Over Drive’ level is set to ‘Off’ or ‘Extreme’ before enabling ‘Adaptive-Sync’, the pixel overdrive will act as if it’s set to ‘Off’ in both cases. If you set it to ‘Normal’ before enabling ‘Adaptive-Sync’, it will act as if it’s set to ‘Normal’. In other words, you can’t use the ‘Extreme’ setting with Adaptive-Sync and you need to set the overdrive level appropriately before enabling Adaptive-Sync. As we explore below, we’d recommend the ‘Normal’ setting for high refresh rates (certainly 144Hz) but ‘Off’ for lower refresh rates – which correspond to expected frame rate ranges if Adaptive-Sync is being used. You can easily save and recall a given ‘Over Drive’ state under Adaptive-Sync by using the ‘G1’, ‘G2’ and ‘G3’ preset modes of the monitor. You can then assign ‘Modes’ to an OSD hotkey so you can easily switch between the different pixel overdrive levels – we run through this procedure in the OSD video.

At 60Hz, above, the UFO appears soft and unfocused without clear internal detailing. This reflects a moderate amount of perceived blur due to eye movement. This is also reflected by the reference displays. Setting ‘Over Drive’ to ‘Off’ provides a strong performance here. It’s the weakest pixel overdrive setting, which is always called ‘Off’ on Acer Predator models, but it’s doing a very good job here at providing suitably fast pixel responses without overdoing things. It’s quite similar overall to the reference shots, slightly faster for some transitions even when compared to the XG240R. The Acer does comparably well with the medium background (middle row) but also performs well for the dark background (top row) and light background (bottom row). There’s just a very small hint of ‘powdery’ trailing in places. The ‘Normal’ setting gets rid of this, but replaces it with quite strong overshoot (inverse ghosting), with colourful trailing behind the object. The ‘Extreme’ setting ramps things up further and provides very strong overshoot that’s impossible to ignore. We consider ‘Off’ to be the optimal setting here. Below you can see how things look with a doubling of refresh rate, to 120Hz.

At 120Hz, above, the UFO appears significantly narrower with clearer internal detailing. This reflects a significant decrease in perceived blur due to eye movement. There are again varying levels of trailing behind the UFO. With the ‘Off’ setting the powdery trailing is now more pronounced than at 60Hz, but by no means extreme. Most noticeably for the dark background, but even then it sticks quite close to the UFO and isn’t as bold as it could be – in other words, it doesn’t have a ‘smeary’ appearance in practice. The increase in ‘powdery trailing’ is due to the significantly increased pixel response requirements for an optimal performance due to a doubling of the refresh rate. The ‘Normal’ setting again curtails this slight ‘powdery’ trailing and replaces it with overshoot. This is strongest for the medium background but is less pronounced than at 60Hz with the same setting. The overshoot is shorter and sharper as well as somewhat more muted at 120Hz. The ‘Extreme’ setting again increases the overshoot, it’s particularly strong with this setting. We’d consider ‘Off’ to be the optimal setting, unless you’ve got reasonable overshoot tolerance in which case ‘Normal’ may be preferred. The images below show things bumped up slightly to 144Hz.

At 144Hz, above, the UFO appears just slightly narrower with slightly better definition. This reflects a slight reduction in perceived blur to eye movement. The trailing behaviour for the ‘Off’ and ‘Extreme’ settings are fairly similar to at 120Hz overall, but the ‘Normal’ setting now exhibits significantly weaker overshoot than it did at 120Hz. It certainly appears that this setting is optimised with this maximum refresh rate in mind and indeed it does a good job. It gets rid of the powdery trailing with the ‘Off’ setting and replaces it with minor overshoot. It gives a performance that’s noticeably improved compared to the 24G2U reference in this test and surprisingly close to the XG240R. Albeit with slightly higher (but still rather minor) overshoot. The ‘Off’ setting is by no means slow, for those who prefer to eliminate the overshoot entirely. There is generally less ‘powdery’ trailing than with the 24G2U reference for all background rows here. See for example the somewhat less extensive trail behind the red UFO body for the dark background – although the yellow cockpit shows some similar weaknesses. What’s clearer is the much shorter and sharper trail behind both the UFO body and cockpit region for the medium background on the Acer when compared to the AOC reference. The AOC isn’t considered a ‘slow’ monitor, either, and is using its most aggressive pixel overdrive setting (‘Strong’) for this comparison. We consider ‘Normal’ to be the optimal setting at 144Hz due to the very clean performance overall with pretty minimal overshoot. But ‘Off’ is a decent fallback if you want to eliminate the overshoot entirely. And certainly makes sense if you frequently find your refresh rate dipping (due to dips in frame rate and Adaptive-Sync active) much below 144Hz.

The monitor has a setting called VRB (Visual Response Boost) that can be activated instead of Adaptive-Sync, if you wish. This is a strobe backlight feature that causes the backlight to flicker at a frequency matching the refresh rate of the display, with 85Hz and 120Hz selectable. Sensitivity to this flickering of the backlight varies and some will find it bothersome whilst others may notice accelerated eye fatigue, even if the flickering isn’t actively bothersome to them. We found 85Hz uncomfortable to use and difficult to adjust to, with 120Hz more palatable by comparison. The pursuit photographs below were taken with the monitor set to 85Hz using VRB set to both the ‘Normal’ and ‘Extreme’ setting. The ‘Extreme’ setting uses a marginally shorter pulse width than ‘Normal’, meaning the backlight spends a relatively long period in its ‘off’ phase. This offers a potential motion clarity improvement at the expense of brightness. Do not confuse the VRB settings (‘Normal’ and ‘Extreme’) with the ‘Over Drive’ settings as they are separate things.

Note that the ‘Over Drive’ setting is adjustable with VRB active, but the ‘Off’ setting is too slow for a comfortable experience and greatly hampers the effectiveness. The ‘Extreme’ setting provides very strong overshoot that’s distracting and difficult to ignore. We there only focus on the ‘Normal’ setting, which is easily the best balanced for this mode.



With VRB active, the main object is significantly narrower with clearer internal detailing. Even at 85Hz and comparing to 144Hz with VRB disabled. The segments are distinct and the notches easy to count. The ‘Extreme’ setting appears to have a slight edge in clarity if you focus on the notches. In practice this difference wasn’t clear and is more due to the higher brightness level of the ‘Normal’ setting bleaching these elements out slightly when captured by the camera. You can see moderate overshoot behind the UFOs for the medium and light background, which is due to the fairly aggressive pixel overdrive used here to help keep conventional trailing at bay. It’s fragmented with multiple repetitions due to the strobing nature of the backlight with this setting active. The dark background shows a repetition of the object in the form of a conventional trail, plus a faint overshoot trail beyond that. The repetitions can be broadly termed ‘Strobe Crosstalk’ and can appear in different places and with different intensity depending on which section of the screen you’re observing. That’s because not all parts of the screen refresh simultaneously – we show and describe the strobe crosstalk throughout the screen a little later on. The images below show the monitor running with VRB set to 120Hz. Some reference screens are included for comparison, the AOC C24G1 using its ‘MBR’ setting and the Dell S2417DG using its ‘ULMB’ settings. These are both quite useable strobe backlight settings and make appropriate references.



The main object again shows excellent clarity, particularly with the ‘Extreme’ setting. Again, the difference between the two settings is somewhat exaggerated by the camera or more to the point the clarity using the ‘Normal’ setting is really quite similar to how ‘Extreme’ is shown here, to the eye. The trailing behind the object, be it conventional trailing (dark background) or overshoot (medium and light backgrounds), is shorter and sharper than at 85Hz simply due to the increased refresh rate. What isn’t shown here is that the flickering is significantly reduced and ‘connected feel’ also improved when comparing the two refresh rates as well, making 120Hz more palatable in general. The AOC reference shows weaker trailing (or strobe crosstalk, if you prefer) than the Acer and is free from overshoot. The Dell reference shows fairly similar overshoot to what is observed with the medium and light backgrounds on the Acer.

In practice the overshoot and conventional trailing shown here by the Acer is significantly weaker than the object itself and therefore doesn’t greatly impede the overall perceived blur with this setting active. We assess this subjectively, shortly. These shots were taken towards the centre of the screen, though, and some regions higher up or lower down the screen show more noticeable strobe crosstalk. This is evident in the image below, pursuit photographs with the screen set to 120Hz and ‘VRB = Normal’. Strobe crosstalk variation at different points was also observed at 85Hz and using ‘VRB = Extreme’, but the relative changes in strobe crosstalk was similar so we didn’t feel it was worthwhile documenting these observations.



Towards the top of the screen you can see strobe crosstalk in front of the intended object. It’s particularly strong further up, where it’s nearly as bold as the object itself and essentially melds into it. There’s also some overshoot behind the object. This overshoot is visible centrally, although there’s no additional strobe crosstalk for most of the central mass of the screen. Towards the bottom of the screen strobe crosstalk is introduced behind the object, essentially replacing the overshoot. At the lowest point shown and a bit above this is fairly bold, although not quite as bold as the strobe crosstalk in front towards the top of the screen. When gaming normally, the central mass of the screen is the main area of the screen you focus on. So it’s good that there isn’t clear strobe crosstalk there – just overshoot that’s quite distinct from and fainter than the main object.

Responsiveness in games and movies

On Battlefield V the monitor provided a fluid experience, with the frame rate keeping up with the 144Hz refresh rate. Compared to a 60Hz monitor (or this monitor running at 60Hz), the monitor is outputting over twice as much visual information every second. This, coupled with the low input lag, provides an excellent ‘connected feel’. Describing the precision and fluidity that’s felt when interacting with the game world and something that low input lag alone can’t provide. As demonstrated using Test UFO earlier, there’s also a significant decrease in perceived blur due to eye movement from the increased refresh rate and frame rate. This gives a competitive advantage on titles like this as it makes it easier to track and engage enemies and keeps the game world more sharply focused during movement.

The monitor did an excellent job in terms of pixel responsiveness, too, making very good use of the 144Hz refresh rate. We had no real complaints in terms of conventional trailing. Very faint whiffs of ‘powdery trailing’ for some transitions, such as white text against a medium-dark background. But this was very slight and affected such a slim number of transitions that it did very little to impact the overall perceived blur. This compared favourably to the AOC 24G2(U), which showed some more extensive ‘powdery’ trailing in places – it’s by no means a slow monitor, but the Acer still has an edge. An area we praised the AOC was overshoot, which was almost non-existent at 144Hz. The Acer did exhibit some overshoot at 144Hz, but it was far from strong and didn’t really stand out. There was a little ‘halo trailing’ in places with trailing that was slightly lighter than the object or background shade. And also a little ‘shadowy’ or ‘dirty’ trailing in places that was slightly darker than the background shade. You can remove this if you wish by setting ‘Overdrive’ to ‘Off’ – but as we’ve explored this only really makes sense where the refresh rate is reduced. The section of video review below runs through the clear strengths and less clear weaknesses in the monitor’s responsiveness.

The monitor provided a similarly fluid experience on Shadow of the Tomb Raider. Whilst the competitive edge was certainly less important here, the fluid experience with reduced perceived blur and superior ‘connected feel’ was still enjoyable. This title showcases many ‘high contrast’ transitions, with dark environments lit up by small light sources and suchlike. These transitions are the sort that will cause some clearer weaknesses on your typical VA model in the form of ‘smeary trailing’ and will cause some potentially heavy ‘powdery’ trailing on many IPS-type models. The monitor provided a strong performance here, traces of overshoot and no real conventional trailing to speak of. So fast and well-tuned pixel responses for 144Hz. We also observed movie content at a range of frame rates, including ~24 – 30fps and 60fps content. There were no clear weaknesses here, with the visual fluidity limited by the frame rate itself rather than the monitor.

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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 XB253Q GP supports FreeSync via DP on compatible GPUs. Note that HDR can be activated (at the same time as FreeSync) via DP 1.4. You need to make sure ‘FreeSync’ is set to ‘On’ in the ‘Game’ 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, ‘AMD FreeSync’ is set to ‘Enabled’ as shown below.



The Acer 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 31fps, for example, the refresh rate would be 62Hz 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 activate the ‘Refresh Rate Num’ setting in the ‘Gaming’ section of the OSD, this will display the refresh rate of the display and therefore indicate the frame rate if ‘FreeSync’ is active and the frame rate is within the variable refresh rate range of the display. 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

As usual we tested a broad range of game titles using FreeSync and found the experience similar in all cases. Any issues identified with FreeSync that were isolated to a specific title would indicate an issue with the game or GPU driver rather than the monitor as well. We’ll therefore just focus Battlefield V for this section. This title provides good flexibility with its graphics options, allowing our RX 580 (far from a beast of a GPU) to be tested across the entire variable refresh rate range of the monitor. With graphics settings set nice and low we were often close to 144fps, with some dips just a little below, perhaps to around 130fps or so. Without FreeSync active, these dips caused obvious tearing if VSync was disabled or obvious stuttering if VSync was enabled. Obvious to us and users sensitive to such things, at least, as it’s important to point out that individual sensitivity varies.

In more intense scenes or with graphics settings turned up a bit, it was common to see the frame rate dip further. Perhaps to 120fps or closer to 100fps. As usual for a monitor with Adaptive-Sync and in contrast with a model with dedicated G-SYNC module, there is no variable overdrive. So as the refresh rate dips due to a decrease in frame rate, increasingly noticeable overshoot kicks in. It happened fairly quickly on this model – as demonstrated using Test UFO earlier, even at 120Hz this is quite a bit stronger than 144Hz. Below that it increases further – so if you’re frequently dipping much below 144fps and using Adaptive-Sync, we’d recommend sticking to the ‘Off’ setting. Which is still quite fast and certainly capable of providing a solid performance, particularly with the lower pixel response requirements of these reduced refresh rates.

With further increases in eye candy came further decreases in frame rate. With frame rates now in the double digits, the loss of ‘connected feel’ and decrease in perceived blur was certainly noticeable when compared to those nice high frame rates. But the lack of tearing and stuttering was a very nice bonus even so. At this point the ‘Normal’ overdrive setting provided some very eye-catching overshoot for some transitions, quite colourful and difficult to ignore. The ‘Off’ setting meanwhile was very nicely balanced here, providing about enough acceleration for optimal performance without noticeable overshoot. Below a certain refresh rate, LFC (Low Framerate Compensation) is used where the refresh rate sticks to a multiple of the refresh rate. This worked as intended to get rid of tearing and stuttering, although as usual there was a momentary stuttering when it activates or deactivates. The exact point of activation was difficult to define exactly – it’s supposed to be 48Hz (48fps), but sometimes seemed to occur as high as 55Hz (55fps). Either way, this should only be a potential concern if you’re frequently passing above or below the trigger point.

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. With the XB253Q GP, you need to connect the monitor up via DisplayPort and enable ‘Adaptive-Sync’ in the ‘Gaming’ 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 and ‘Enable settings for the selected display model’ is checked as shown below. Press OK, then turn the monitor off then on again so that it re-establishes connection – the technology should now be active.

Update: As of driver version 461.40, this model is officially certified as ‘G-SYNC Compatible’. Which means it has been specifically tested by Nvidia and passes various quality checks with the technology working as it should. Issues highlighted here shouldn’t be expected, certainly not with newer GPUs.



You will also see in the image above that it states: “Selected Display is not validated as G-SYNC Compatible.” The image is for a different model, but exactly the same information is displayed for the Acer (aside from the model number, of course). This means Nvidia hasn’t specifically tested and validated the display. Acer seems to market the monitor as if it is ‘G-SYNC Compatible’ and certified as such, but this isn’t confirmed in the driver. And at time of review, the ‘GP’ model isn’t listed on Nvidia’s website as certified. On our GTX 10 Series GPU (GTX 1080 Ti), the technology worked to a degree, but didn’t quite do what it should. It would frequently disable itself momentarily or cause significant mismatches between frame and refresh rate. It was effective in reducing tearing (within its window of operation) and stuttering, but we observed some stuttering and slight tearing that corresponded to the frequent mismatches in frame and refresh rate. The tearing wasn’t as frequent or obvious as with the technology disabled and VSync disabled, whilst the stuttering wasn’t as frequent or obvious as with the technology disabled and VSync enabled. It was strange having a bit of both, though, and this shouldn’t occur with ‘G-SYNC Compatible Mode’ working correctly. Newer GPUs such as the RTX 20 and RTX 30 series should fare better. We’ve observed various issues on other monitors using ‘G-SYNC Compatible Mode’ that seem to only apply to older GPUs like ours but not newer generation GPUs such as the RTX 20 series. Either way, we still found the technology useful and preferred having it enabled over disabled – it didn’t have ‘deal breaking’ issues such as screen blanking or potentially obnoxious flickering and still reduced tearing and stuttering. This section of the video review runs through the technology and some of the issues we described above when using it on our GTX 1080 Ti.

Our suggestions regarding use of VSync also apply, but you’re using Nvidia Control Panel rather than AMD Radeon Software 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, remember that you can activate the ‘Refresh Rate Num’ setting in the ‘Gaming’ section of the OSD to display the current refresh rate of the monitor. This will reflect the frame rate if it’s within the main variable refresh rate window, with the additional fluctuations described above possible depending on your GPU. And as with AMD FreeSync, HDR can be used at the same time as ‘G-SYNC Compatible Mode’.

VRB (Visual Response Boost)

Earlier in the review, we introduced the ‘VRB (Visual Response Boost)’ feature, its principles of operation and how it performs using specific tests. When using VRB or a similar strobe backlight feature, you must have your frame rate synchronised properly with the refresh rate of the display. If that isn’t the case you’re left with extremely obvious stuttering or juddering. This stands out in a particularly obvious way 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 VRB and you’re limited to relatively low brightness levels, as explored earlier. As a reminder, we recorded a maximum luminance of 88 cd/m² and most users prefer brightness levels significantly higher than that, typically 120 cd/m² – 200 cd/m² and sometimes higher. Some will find this brightness level fine and will adjust to it, particularly if the room isn’t too bright. We tested this setting using various game titles, but for simplicity we’ll simply be focusing on Battlefield V running at a solid 120fps and monitor set to 120Hz for this section. The observations here are largely reflected at different refresh rates or VRB settings – we prefer ‘Normal’ as ‘Extreme’ is simply too dim for our taste. And we prefer 120Hz due to lower flickering and superior ‘connected feel’, although 85Hz can be a nice fallback if you can’t sustain a solid 120fps and you don’t mind stronger flickering.

This setting performed its main function effectively, massively reducing perceived blur due to eye movement. Further up and down the screen there was noticeable strobe crosstalk, the repetitions of the object that was demonstrated using Test UFO earlier. This affected the motion clarity in those regions. However; when gaming competitively, which is the main focus of this mode, you tend to fixate on the centre of the screen. This region did not exhibit this strobe crosstalk, instead just showing some overshoot in places. Which was much fainter than the object or any background textures during motion. Rapid turns of the character or manoeuvring quickly in a vehicle was not accompanied by the blurring of the background and loss of detail that occurs with VRB disabled. The level of clarity and overall detail (low levels of perceived blur, in other words) in that central mass of screen was excellent. So whilst this wasn’t the cleanest strobe backlight setting we’ve seen, it was far from the worst. And actually quite useable for those who are happy to put up with the drawbacks and find the competitive edge it brings attractive.

HDR (High Dynamic Range)

Under HDR (High Dynamic Range), an ideal monitor is able to simultaneously display very deep dark shades and very bright light shades. Additionally, an excellent range of shades between these extremes can be shown, including very eye-catching vibrant shades as well as a good palette of much more muted shades. Ideally, per-pixel illumination would be used (backlightless technology such as OLED, for example). Failing that, a backlight solution such as FALD (Full Array Local Dimming) with a great number of dimming zones is desirable. This allows some areas of the screen to display very deep dark shades whilst other areas display brilliant bright shades. Colour reproduction is also an important part of HDR. The long-term goal is support for a huge colour gamut, Rec. 2020. A more achievable near-term goal is support for at least 90% DCI-P3 (Digital Cinema Initiatives standard colour space) coverage. 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.

The HDR10 pipeline is the most widely supported HDR standard used in HDR games and movies and the pipeline supported by this model. Unlike most HDR-capable monitors, the Acer XB253Q GP does not automatically switch into its HDR operating mode when an HDR colour signal is detected. You must do this manually – there are various ways to do this. You can set ‘HDR’ to ‘Auto’ or ‘HDR-400’ in the ‘Picture’ section of the OSD (both settings seem to be identical). Or selecting ‘HDR’ as the ‘Mode’ or ‘Color Space’ in the ‘Color’ section of the OSD. 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 and monitor 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 is really just a digital brightness slider, so you lose contrast by adjusting it. The balance of the image was a lot better than most models displaying SDR content with HDR enabled, but you get a loss of normal brightness control, colour channel adjustment and some gamma inconsistencies. 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 simplicity we’ll just focus on two game titles for this section; Battlefield V and Shadow of the Tomb Raider. These are titles we’ve experienced on a broad range of monitors under HDR and we know they are good at highlighting strengths and weaknesses in the HDR performance. Providing a good HDR experience if the monitor is capable enough under HDR. The experience we describe here is largely dictated and limited by the screen itself. Although our testing here is focused on HDR PC gaming using DisplayPort, we made similar observations using HDMI. The observations apply to other HDR content, such as movies, and also running HDR on compatible games consoles. Usually a sharpness filter is applied under HDR to accentuate some of the enhancements it makes. In this case it can be manually enabled by enabling ‘Super Sharpness’ in the ‘Picture’ section of the OSD. Or left disabled, which is our preference on this model.

The Acer XB253Q GP is VESA DisplayHDR 400 certified. This is the lowest level of certification that VESA certifies for and therefore means that only a basic HDR experience is offered. One area that the VESA DisplayHDR 400 requirement isn’t too strict about is colour gamut. As mentioned earlier, good coverage of the DCI-P3 colour space is desirable. In this case the colour gamut only covers 81% of the DCI-P3 space, as shown in the gamut representation below. The red triangle shows the colour gamut of the monitor, whilst the blue triangle shows the DCI-P3 reference space. The image didn’t looked ‘washed out’ exactly, but in general shades were somewhat more muted in appearance than under SDR. There was just a general lack of depth, plus a bit of a cool tint which couldn’t be adjusted for in the OSD due to locked colour channels. These being locked off isn’t unusual for HDR, however. The poor colour gamut by HDR standards meant that there weren’t some of those elements of real vibrant pop that can sometimes be offered over HDR. On Battlefield V, for example, roaring flames didn’t have the rich and vivid intense oranges you’d sometimes see, whilst deep paint colours and lush forest greens were less saturated than they could be. On Tomb Raider there were elements like deep purple flowers, dark blue dresses and flows of lava that lacked the sort of HDR intensity we’d expect. Environments and skin tones still looked quite natural and had reasonable richness and at least Acer didn’t try to make up for the lack of gamut coverage with clear digital oversaturation or quirky gamma behaviour.

Colour gamut 'Test Settings'

The monitor supports a 10-bit signal via 8-bit + FRC. The enhanced precision of the 10-bit signal helps enhance the nuanced shade variety, giving a more believable look to shaded areas. It helps lift out detail in a natural way, with a superior range of very closely matching dark shades. This is very different to the artificial or flooded appearance that some sort of gamma tweak would achieve. This enhanced nuanced shade variety is also easy to appreciate at the high end. Fine gradients such as areas of sky, mist, smoke and suchlike are displayed much more smoothly with more gentle progressions between shades. The image below is from Shadow of the Tomb Raider and is one of our favourite scenes under HDR to help highlight the strengths and weaknesses of a monitor’s HDR performance from a contrast perspective. Remember that the photo is purely for illustrative purposes and in no way represents how the monitor appeared running HDR in person. Note that vertical lines on lighter areas of the image are moiré from the camera, not observed on monitor.

The scene certainly highlighted the nuanced shade variety nicely, with the mist and light rays showcasing some excellent smooth gradients. Things certainly didn’t look as eye-catching or impressive as they could from a contrast perspective, though. VESA DisplayHDR 400 does not mandate any local dimming and has a more restrictive brightness requirement than higher DisplayHDR levels. The bright light streaming in from the sky and the glints of light on the water and waxy leaf surfaces just didn’t have the eye-catching pop that much more capable HDR performers provide. Meanwhile, the darker shades lacked the depth that they should have. Daylight scenes like this therefore didn’t have that natural brightness range that defines a proper HDR experience and makes such scenes look more believable in many respects. Darker areas certainly highlighted limitations in the HDR performance, too. The backlight brightness control of the Acer is really rather unusual under HDR. You can set the brightness before the HDR signal is detected, by selecting the ‘HDR’ mode with an SDR signal selected. The monitor will then respect the brightness level you’ve selected when the HDR signal is detected. We found lower brightness settings to be particularly far removed from any semblance of ‘HDR’ and preferred just leaving this at the default of ‘100’.

Another peculiarity is that the monitor doesn’t employ effective Dynamic Contrast, which is usually used under HDR combined with HDR meta data to enhance precision. Whilst the merits of this are debateable and it doesn’t compare to a solution that also uses effective local dimming, it does at least help maintain better dark atmosphere for very dark scenes where global dimming is used. We observed gamma adjustments, which were strangely gradual at times, when switching from a bright to dark scene. Dark elements becoming increasingly detailed over the course of a few seconds, without the darkest elements appearing any deeper. That’s because the backlight itself seemed to remain set at the same level. This meant that even for predominantly darks scenes the black depth was as high as it would be under SDR with a high brightness level set, giving a ‘flooded’ look. Unless you selected a lower brightness level before the colour signal activated, in which case the bright elements would simply remain looking dull with distinctly ‘non-HDR’ luminance levels. It’s possible these sort of gamma changes are common under HDR, but they’re usually accompanied by backlight brightness changes which make them seem more natural and in-place. Whichever way you cut it, this was a very basic and in many ways quite flawed HDR experience. The HDR experience using Shadow of the Tomb Raider as an example is explored in the relevant section of video review below.

Video review

The video below shows the monitor in action. The camera, processing done and your own screen all affect the output – so it doesn’t accurately represent what you’d see when viewing the monitor in person. It still provides useful visual demonstrations and explanations which help reinforce some of the key points raised in the written piece.

Timestamps:
Features & Aesthetics
Contrast
Colour reproduction
HDR (High Dynamic Range)
Responsiveness (General)
Responsiveness (Adaptive-Sync)

Conclusion

The fluidity of a 144Hz monitor can provide can be very attractive for both casual and competitive gamers. With improvements to pixel responsiveness, we’ve seen a general shift in the market away from TN models towards more ‘colour-capable’ monitors with IPS-type panels. The Acer XB253Q GP is one such product, wrapping things up into the familiar ‘Predator’ package. The stand offers full ergonomic flexibility and has quite a weighty and premium feel to it courtesy of the powder-coated metal base. The OSD offers a good range of adjustment options for those who like to fine-tune things. Whilst some options were implemented in a fairly quirky way, such as the ‘Over Drive’ control with Adaptive-Sync active and ‘Brightness’ control under HDR, the core functionality was good. And we appreciated the ease of storing and recalling preferred settings using the ‘G1’, ‘G2’ and ‘G3’ presets. The Full HD resolution and 24.5” screen size doesn’t provide a staggering pixel density or indeed fantastic desktop real-estate, but we feel it’s a comfortable screen size for the resolution and it’s a relatively easy one to drive at decent frame rates.

The contrast performance was largely in-line with our expectations, if not slightly above them. The static contrast readings weren’t quite up there with the lofty heights achieved by the AOC 24G2(U), with its 1400:1 recorded under our ‘Test Settings’. But they weren’t too far off and also comfortably exceeded the specified 1000:1, at a touch above 1200:1 under our ‘Test Settings’. This certainly doesn’t deliver amazing depth or ‘inkiness’ to dark scenes, particularly if sitting in a dimly lit room. And ‘IPS glow’ eats away at that atmosphere and detail further. But it was a bit of an improvement over some IPS models which struggle to even reach the specified 1000:1. The screen surface was not quite as smooth as on the aforementioned AOC, either, although didn’t impart the sort of ‘smeary’ graininess that some matte anti-glare solutions provide. It was quite in-line with many 144Hz Full HD TN models, which many users happily use without giving too much thought to the screen surface.

The monitor was calibrated quite nicely ‘out of the box’, certainly in terms of gamma. So following just a little tweaking the IPS-type panel delivered an image that was ‘rich and natural’ and also very consistent. The experience was somewhat different to on the AOC 24G2(U). The colour gamut on the Acer only extends a little beyond sRGB, inviting a touch of extra vibrancy whilst keeping things faithful to the original developer intentions. The AOC’s output is more vibrant and saturated, although still very varied due to it being achieved with a fairly generous colour gamut rather a digital saturation boost. An effective sRGB emulation setting is also included on the Acer, which doesn’t lock off the brightness control (yay) but does restrict some other settings like colour channel adjustment. It curtails that slight over-extension beyond sRGB. Again drawing on that comparison with the AOC, the colour consistency of the Acer was superior. Whilst both models have an IPS-type panel, the AOC exhibited some shifts in saturation and a noticeable dulling of some shades towards the edges of the screen. The Acer provided your classic IPS-type consistency, with good richness maintained throughout the screen. In both cases your mileage may vary a bit due to potential uniformity issues which can vary between individual units.

The monitor offers HDR support, although only at a basic level. VESA DisplayHDR 400 certification, the lowest level that VESA certifies for. And rather odd brightness regulation, without the usual Dynamic Contrast enhanced with HDR metadata. This left scenes looking quite bright overall, even if they were dominated by dark shades. This could be counteracted only by reducing brightness in the HDR OSD setting (which, oddly, doesn’t automatically activate under HDR) before an HDR signal is detected. You’d then be left with bright elements looking rather dull and not at all ‘HDR-like’. But of course, without any local dimming and fairly limited maximum luminance things were never going to look too spectacular under HDR anyway. Coupled with a colour gamut that’s far more limited than the near-term DCI-P3 standard, HDR on this monitor is more there for a bit of variety and occasional usage. It does make games look ‘different’ and you can benefit from 10-bit colour processing to improve nuanced shade variety and smooth out gradients. But it’s certainly not specular nor a reason to buy this model.

One reason you certainly might want to buy this model, aside from its colour reproduction characteristics, is responsiveness. The monitor provided a very convincing 144Hz performance. The pixel responses were tightly tuned and heavily optimised with this refresh rate in mind using the ‘Normal’ setting for ‘Over Drive’. There was a touch of overshoot, but nothing extreme – and really very little to complain about in the way of conventional trailing. A step above the AOC 24G2U, which is no slouch at 144Hz, with less ‘powdery trailing’ in particular where medium to darker shades are involved. In fact this model would put quite a few TN models to shame with its level of pixel responsiveness. Coupled with a low level of input lag, the ‘connected feel’ and perceived blur levels were as you’d hope from a solid 144Hz performer. The monitor’s VRB strobe backlight setting was quite useable, provided you don’t mind the drawbacks (including limited brightness and the unavoidable flickering). Strobe crosstalk was minimal in the central region of the screen, but quite strong towards the top and bottom – fortunately, it’s the centre of the screen that will be your main focus during competitive gaming. The monitor also supports Adaptive-Sync, which worked with both our AMD and Nvidia GPUs to get rid of tearing and stuttering. Likely due to a quirk with our older (GTX 10 series) GPU, ‘G-SYNC Compatible Mode’ didn’t work perfectly due to some departures between frame and refresh rate. But it was still nice to have and reduced tearing and stuttering, even if they weren’t entirely eliminated. The lower level of overdrive (‘Off’) proved its worth where the frame rate (and hence refresh rate) dropped, whilst still being quite useable at much higher refresh rates as well.

We’ve been drawing the comparison throughout this review with the AOC 24G2U as this is a very interesting and pertinent comparison to draw. In summary, the AOC is the cheaper monitor in part as it’s based on a 23.8” Panda IPS-type panel rather than the 24.5” AUO panel of the Acer. The AOC offers some potential advantages aside from cost, including having a smoother screen surface, slightly (but not substantially) stronger static contrast and more vibrant colour output. The Acer, on the other hand, offers rich and natural colour output with superior consistency. According to our own findings and user feedback we’ve received, the AOC’s panel is more prone to uniformity issues than the Acer’s panel. The Acer offers higher peak luminance and HDR support, although the AOC is more than bright enough for most users (and comfortably exceeds its specifications). And, of course, the HDR on the Acer is nothing to write home about. The Predator offers superior pixel responsiveness, surprisingly TN-like at 144Hz with its ‘Normal’ pixel overdrive setting. The strobe backlight setting is more useable on the Acer, too, due to lower central strobe crosstalk. It has a more robust ‘feel’ and arguably more premium look due in large part to the powder-coated metal stand. Whilst we don’t make a big thing about it in either review, the Acer also offers true 8-bit colour output vs. 6-bit + FRC dithering on the AOC. It’s finely controlled dithering and for most users it won’t make a difference, but we do know some appreciate the lack of dithering that the XB253Q GP provides. Overall, this is a competent gaming monitor, offering a pleasing mixture of colour quality and responsiveness. It’s well built, feature-rich and importantly performs well without any deal-breaking weaknesses.

The bottom line; a capable, highly responsive and well-tuned monitor with rich and natural colour output.

Positives	Negatives
A rich and natural look to the image with strong consistency and good ‘out of the box’ gamma. Good OSD flexibility to tweak gamma and colour representation	Some may prefer the extra vibrancy and saturation provided by a wider colour gamut
Decent contrast a bit above specifications and strong gamma consistency from IPS-type panel, basic HDR support	‘IPS glow’ eats away at detail and atmosphere. Screen surface gives a bit of a grainy appearance to lighter shades. HDR support limited and quite strangely implemented
Well-tuned pixel responsiveness for a solid 144Hz performance, low input lag and Adaptive-Sync assisting with stuttering and tearing on both our AMD and Nvidia GPU. VRB will have good utility for some due to low central strobe crosstalk	No variable overdrive, optimal setting for 144Hz gives strong overshoot much below that – the lower overdrive level works nicely in such situations. Some issues with Adaptive-Sync on our Nvidia GPU, but it still helps. Newer Nvidia GPUs should work without these hiccups
Quite solidly built with solid powder-coated metal base, good ergonomic flexibility and a feature-rich OSD	Full HD resolution quite limited in terms of pixel density and desktop real-estate, ‘gamery’ aesthetics won’t appeal to everyone and pricing fairly high for a 144Hz Full HD model

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