ASUS PG27AQ

Responsiveness

Input lag

A sensitive camera and tool called SMTT 2.0 was used to compare the latency of the PG27AQ with a range of monitors of known latency. By taking over 30 repeat readings to enhance accuracy, we calculated 5.9ms (just over 1/3 of a frame) of input lag. This value is influenced by the pixel responsiveness (element you see) and signal delay (element you feel). It indicates a very low signal delay which shouldn’t hamper the experience even for sensitive users.

Perceived blur (pursuit photography)

In our responsiveness article we explore the key factors that influence how responsive a monitor looks and feels when we use it. The notion that eye movement is usually the predominant contributing factor to perceived blur on a monitor, with pixel responsiveness of secondary importance, is chief amongst these factors. It is possible to capture motion on a monitor in a way that demonstrates the influence of this eye movement as well as pixel responsiveness. This is called ‘pursuit photography’, explored in the article, whereby a moving rather than stationary camera is used to capture motion on the monitor.

Pursuit photographs were taken using the UFO Motion Test for ghosting, using a sensitive camera. The test was set to run at 960 pixels per second, which is a practical speed for such photographs and helps highlight the key influencers of perceived blur. The middle row of the test (light cyan background) was used with the monitor set to its three different ‘OD’ (Overdrive) settings; ‘OFF’, ‘Normal’ and ‘Extreme’. The results are shown in the image below, alongside the results of a ‘Fast 60Hz reference’. This is a Samsung S27A750D set to full brightness (prevents PWM usage), at 60Hz, using its ‘Faster’ response time setting. This shows how things will look where motion blur due to eye (camera) movement is the only real limiting factor.

Perceived blur with various settings

With ‘OD = OFF’ you can see a slight trail behind the object as a result of slower than optimal pixel responsiveness. This is far from obtrusive and is much more constrained than you’d expect to see from a monitor of any panel type if the pixel overdrive feature is disabled. Really ‘OFF’ is a bit of a misnomer as it’s quite clear that the monitor is using quite a well-balanced level of grey to grey acceleration here and it is not entirely absent as the name would suggest. With ‘OD = Normal’ the trailing is reduced but has instead been replaced by a mild to moderate degree of ‘inverse ghosting’ (overshoot). This brightly coloured trail behind the object is caused by overly aggressive pixel overdrive, with the monitor surging extra voltage to try to speed up pixel transitions but actually causing them to ‘overshoot’ the desired end point for the transition. The ‘OD = Extreme’ setting shows intense inverse ghosting, with strong overshoot indicative of extremely over-aggressive pixel overdrive.

From this analysis and moreover general use of the monitor we preferred to use ‘OFF’ for the ‘OD’ setting’. If this was actually a setting where pixel overdrive was entirely absent, we would most likely have stuck with the default ‘Normal’ setting instead’. However; this mode provided only a faint whiff of trailing on top of the perceived blur from eye movement and this was far less distracting in our eyes than the overshoot under the ‘Normal’ and ‘Extreme’ settings. In the following analysis we note our observations whilst gaming, where a much broader pixel transition range and more complex scenes are involved compared to this test. Note that there will not be a section on ‘overclocking’ as the monitor could only be set a couple of Hz above 60Hz before it went out of range. This provided no noticeable benefit over 60Hz.

Responsiveness in games and movies

On Battlefield 4 (BF4) there was little weakness beyond the moderate degree of motion blur attributed to eye movement. The pixel responsiveness was pretty much right where it needs to be for optimal 60Hz performance. There was a small degree of trailing on top of the blur from eye movement, but it was really rather faint and didn’t catch the eye in the same way as the overshoot with ‘OD’ set to ‘Normal’ sometimes would. Even for medium-dark shades moving against one another, seen for example moving quickly amongst shaded areas of vegetation, there was not the degree of trailing you would see on some ‘4K’ UHD models (particularly, rather ironically, those with TN panels).

Dirt Rally again highlighted that this monitor is quite a capable 60Hz performer. There was a moderate degree of blur even when cornering quite generally, but this was attributable to eye movement and tied to the 60Hz refresh rate rather than sluggish pixel responsiveness. The slight additional trailing on top of this, from some slightly slower than optimal pixel responses, was preferable and less noticeable than the overshoot that replaced it with the other ‘OD’ settings. It was quite clear that this monitor has effective and well-balanced grey to grey acceleration levels for 60Hz, but only with the appropriate setting which is rather misleadingly labelled ‘OFF’.

We also tested out our Blu-ray movie test titles to observe for weaknesses in pixel response performance. There were no weaknesses whatsoever attributable to the pixel responsiveness of the monitor – nor any observable overshoot. The overall fluidity of the motion here was limited by the ~24fps frame rate of these film titles.

G-SYNC – the technology and activating it

Nvidia G-SYNC is a variable refresh rate technology which is explored in our dedicated article on the topic. In a nutshell, its aim is to adjust the refresh rate of the monitor ‘on the fly’ to match the frame rate of the content being displayed. As explained in the article, this eliminates both the stuttering you get with VSync on and the tearing and juddering you get with VSync off. In the variable frame rate (and hence variable refresh rate) environment, latency is also significantly reduced compared to VSync on. Unfortunately, we do not have the means to empirically and accurately measure this latency difference.

To enable G-SYNC, you need a compatible monitor (such as the PG27AQ) which has a dedicated ‘G-SYNC board’ that replaces the traditional scaler and many of the assistive electronics of the monitor. You also need a compatible GPU, such as the Nvidia GTX 970 that we’re using, connected via DisplayPort (version 1.2 or higher). This feature was enabled automatically when we connected up this monitor, but if it isn’t then enabling it is a simple case of visiting the Nvidia Control Panel. Navigate to ‘Display’ – ‘Set up G-SYNC’ and ensure the ‘Enable G-SYNC’ checkbox is ticked as shown below. You can also use the technology when an application (such as a game) is running in windowed mode and not just full screen by selecting the appropriate option on this page.

In ‘Manage 3D settings’ you can either enable or disable VSync. Nvidia advises using this to control VSync and making sure it is set to ‘off’ in any game as in-game VSync can apparently upset things. The monitor has a variable refresh rate range of 30 – 60Hz, outside of which the GPU will respect your choice of ‘VSync on’ or ‘VSync off’. If you choose ‘VSync on’, the maximum frame rate of the content will be capped to 60fps and if it reaches this VSync is enabled. If you choose ‘VSync off’ then the GPU will use G-SYNC as before, but will exceed 60fps and introduce tearing as the monitor will be set to a 60Hz refresh rate but no higher. If the content dips below the 30Hz (30fps) floor, the monitor will try to set its refresh rate to a multiple of the refresh rate to minimise or eliminate stuttering and tearing as well. As noted below, low frame rates are still low frame rates – but it’s nice to have things as smooth as they can be for a given frame rate.

G-SYNC – the experience

Star Wars Battlefront is a rather well-optimised game, but still very demanding when running at 3840 x 2160 – especially with some of the detail settings turned up a bit. Without a variable refresh rate technology such as G-SYNC, even the slightest dips below 60fps would lead to rather jarring stuttering (VSync on) or obvious tearing and associated juddering (VSync off). With our single GTX 970, we’d have to make considerable sacrifices to visual quality if we wanted to maintain a fairly consistent 60fps. And even then, there would be some inevitable dips. On this monitor, with G-SYNC, we were able to set the monitor to more visually appealing settings. The slight dips below 60fps were frequent, with the monitor generally maintaining >50fps most of the time. Unlike with the variable refresh rate technology disabled, this was free from stuttering, tearing or juddering and just generally felt more fluid and was more enjoyable as a result. There were times when the game dipped closer to 40fps and when the action was extremely intense on certain interior areas, even dropped slightly below 30fps. The experience was again free from stuttering or tearing and therefore preferable to the experience of hitting such frame rates without G-SYNC. And indeed the technology was able to effectively compensate for frame rates below the floor of operation (30Hz or 30fps) by setting the refresh rate to a multiple of the refresh rate. However; it was nothing like gaming at higher frame rates, particularly close to 60fps. The level of motion blur was considerably higher and you simply felt more disconnected from the game world with an increased delay between frames translating to a poorer gameplay experience.

BF4 enforced similar points. Again, the frame rates on this title are highly variable. With frequent dips below 60fps with settings we like to use, it was very nice indeed being able to maintain a stuttering and tearing free gaming experience. These dips were far less jarring than without the technology enabled. Again, there were times when the frame rate dropped even lower and there is no pretending that this couldn’t be felt. G-SYNC certainly makes such drops a lot more palatable, as you aren’t hit by horrendous levels of stuttering or tearing. However; low frame rates are still low frame rates. The technology is not a magic bullet that can change that. It’s still a sub-optimal experience, but it’s certainly superior to the static 60Hz alternative.

We tested a number of other titles including The Elder Scrolls Online, Dirt Rally and Titanfall. All of these titles saw benefit from G-SYNC and it made these games more playable at decent graphics settings than they would be otherwise. Again, low frame rates are low frame rates. But regardless of frame rate, it was nice having an experience free from the stuttering, tearing or juddering caused by frame rate and refresh rate mismatch.

The ‘4K’ UHD experience

In this article we explore the benefits and drawbacks of the 3840 x 2160 ‘4K’ UHD resolution. The piece was written with respect to the experience of using a 28” UHD model – but needless to say, 27” UHD models such as this ROG SWIFT offer a very similar experience. We’d therefore advise reading the article to familiarise yourself with some key points such as how scaling is handled (and generally required) on modern versions of Windows with a monitor of this pixel 163.18 PPI (Pixels Per Inch) pixel density. Our preferred scaling level for this was ‘125%’, which still retained significant real-estate benefit from the resolution whilst ensuring things were comfortably readable for us. Obviously personal preferences for scaling level will vary. The top image below shows how the desktop appeared using ‘125%’ scaling, the same image used earlier on in the review. The bottom image shows the multi-tasking potential using this setting with a website open on the left and a Microsoft Excel Spreadsheet on the left. Everything was crisp and readable with plenty of detail on the images – and of course, lots of content on the screen at the same time.

The take home message is essentially that we find the ~32” screen size to be something of a sweet spot for the UHD resolution. It provides a comfortable viewing experience without scaling for us from our preferred viewing distance of ~70cm – although mileage may vary according to preferences, eyesight and preferred viewing distance. This provides a large working area both in terms of physical space but also, importantly, useful work area. Text and image clarity is excellent and you can fit a lot on the screen at once, as demonstrated by the images below.

As the article points out, scaling can be a bit hit and miss depending on the software you’re using with some handling it better than others. Regardless of which scaling setting you choose to use, many applications offer you independent zoom control for their main content area. The scaling setting will generally change the default zoom level used, but you can zoom in or out regardless of this. Most people are familiar with how this works on web browsers, for example. Our experience running games and movies in the UHD resolution was much as we observed on the 28” screen featured in the article. The following images are simply for illustrative purposes and do not in any way represent how things looked on the monitor first-hand.

You will likely notice that most of these images are of Star Wars Battlefront, which we didn’t test in the original article as it wasn’t released at the time. This made excellent use of the UHD resolution, with very high quality textures used extensively. Although clearly set in a fantasy world, the environments on the game are actually based on real world locations. The lush forests of Endor, for example, are based on Muir Woods in California. The resolution of the monitor really helped give a life-like quality to the vegetation – it appeared extremely crisp, sharp and detailed (especially with the graphics quality cranked up a bit) in a way that just isn’t captured on models with lower resolutions such as 2560 x 1440. Even decomposing foliage on the forest floor had a realistic crispness and detail to it, as did the boggy areas of squelchy mud. The exceptional lighting quality and realistic shadows in the game helped intensify this experience. But it wasn’t just on Endor where the resolution helped create an impressively realistic look. The inhospitable snow-covered planet of Hoth (based on the landscapes of Finse in Norway) had an appropriately grainy look to the snow, with a certain structural quality of it that simply isn’t captured well at lower resolutions. The rough rocky surface of Sullust (based on Iceland) were equally impressive, with their subtle pores and imperfections captured and displayed beautifully.

But it wasn’t just the environments that took advantage of the excellent pixel density of the monitor. The textures used on character models were also good, especially on the ‘heroes’. The tarnished paint and specular highlights on Boba Fett’s apparel and the material texture of Emperor Palatine’s cloak were particularly impressive. And indeed the extra detail and sharp look to things helped the ‘special effects’ (explosions, sparks, weapon fire and other energy pulses) to stand out in a rather satisfying way. Really there were no textures in the game that looked poor or out of place – they all seemed to take good advantage of the UHD resolution, provided the texture resolution setting of the game was set to a suitably high level.

Interpolation and upscaling

The 3840 x 2160 ‘4K’ UHD resolution requires considerable graphical grunt to run on demanding applications, such as some games. Users may therefore consider running a lower resolution such as 1920 x 1080 – and indeed if they are connected to a modern games console, this sort of lower resolution will be all they can use. If you connect the monitor up to a PC via DP 1.2, the interpolation (scaling) process is handled exclusively by the GPU. There is significant softening to the image compared to running the resolution natively, whether you select 1920 x 1080 (Full HD), 2560 x 1440 (WQHD) or something else. Whilst gaming, it looks as if you’re looking at the game world through a soft-focus lens.

If you’re connected using HDMI, either to a PC or games console, the monitor does have scaling features and will be able to use its own interpolation processing to handle non-native resolutions. As a PC user you should ensure that the monitor rather than GPU is handling this. If you’re using an Nvidia GPU (more likely with this monitor) you should open the Nvidia Control Panel and navigate to ‘Display – Adjust desktop size and position’. Ensure ‘No Scaling’ is selected and ‘Perform scaling on:’ is set to ‘Display’ as shown below. AMD GPU users shouldn’t need to change anything as the drivers are set up so that the monitor will handle interpolation, where possible, in games.

When the monitor uses interpolation, over HDMI, there is less softening than when the GPU handles the interpolation. There is still a moderate degree of softening – the 1920 x 1080 resolution isn’t mapped ‘perfectly’ as some users might expect given the even division of pixels into the native resolution (1:4). We’d say it’s usable, and more so than using GPU scaling, but it is far from ideal and really isn’t close to the sharpness of a native Full HD display of similar size. The 2560 x 1440 resolution works a bit better in terms of its ‘visual closeness’ to native 27” WQHD displays, but is pretty much unbearable to use due to the 24Hz refresh rate that is enforced with this over HDMI. Getting this resolution to display correctly at anything much over this was impossible even with a custom resolution as the monitor employed interlacing and introduced various artifacts.

Conclusion

There are certainly advantages to the ‘4K’ UHD resolution, but it also comes with its drawbacks. One of the key drawbacks, for gamers, is that it requires an immense amount of graphical horsepower to run with decent settings on modern titles. Unless, of course, you’re happy to let the frame rate drop well below the refresh rate of the monitor and suffer through the stuttering or tearing that comes with that. With support for Nvidia G-SYNC, the PG27AQ cuts out the tearing and stuttering that would otherwise occur by ensuring the frame rate matched the refresh rate of the game (as far as possible). In doing so, it certainly made drops below 60fps far more palatable. Although it smoothed out the experience in the variable refresh rate environment, it isn’t a magic bullet. Low frame rates are still low frame rates regardless of G-SYNC – and the optimal experience was gained with the frame rate as high as possible.

On the topic of frame rate and refresh rate, the 60Hz maximum refresh rate won’t necessarily appeal to some gamers who prefer the fluidity offered by higher refresh rates. Unfortunately, the connectivity options to bring about higher refresh rates aren’t currently out there in the open. And even if they were it would only be those blessed with stellar systems that could really take proper advantage of them. Within the confines of the 60Hz maximum, though, the PG27AQ put in a good performance. Using the optimal pixel overdrive setting, which is rather misleadingly labelled ‘OFF’, there was little weakness on top of what you would see on even the fastest artifact-free LCDs. Pixel responses were snappy enough so that you didn’t get obvious trailing on top of the perceived blur you’ll always get on a 60Hz sample and hold monitor. And input lag was about as low as we’ve seen on a UHD display and was indicative of a very low signal delay.

The colour reproduction of the screen was also pleasing, overall. The gamma tracking was excellent straight from the box, which is just as well as you have no flexibility over this on the OSD. The new ‘GameVisual’ presets tended to mess up the image with unnecessary and shade-range-killing levels of saturation or various other image imbalances. The exception to this was the default ‘Racing Mode’, which certainly optimal for appealing natural colours and helped make the most out of the AHVA panel. Colours were consistently rich throughout the screen. The full sRGB coverage with a little extension beyond plus the very light matte screen surface aided the apparent vibrancy, too. It has to be said, though, that the screen surface texture wasn’t quite as smooth as we would have liked and that did provide a bit of a grainy look to white and other light shades.

The contrast performance was very much as you’d expect from a modern IPS-type panel. Decent static contrast and the ability to display a good range of distinct dark shades in the centre of the screen, but some weaknesses peripherally due to ‘AHVA glow’. We also have to step back a bit from the panel and the monitor’s image performance and say that we certainly liked the construction of the monitor. It was solid and in our opinion not ‘tacky’ in the way some gaming monitors are. Overall this monitor put in quite a solid performance, as you’d hope for given the price. It certainly had its weaknesses, but we have yet to use a monitor that’s perfect.

The bottom line; a solid but pricey gaming monitor for those who like to admire the eye-candy whilst gaming and are content with a 60Hz maximum refresh rate.

 

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