Asus PQ321Q review - eyes-on with the first 4K PC display

Tomorrow's technology today.

Battlefield 4: already demoed at 4K/60fps by DICE on extreme high-end PC hardware.

While the next generation of consoles are finally set to deliver 1080p gaming to the masses, the consumer electronics industry is rapidly gearing up for a full-scale push towards 4K - the next standard in high definition viewing. 4K, or 3840x2160 Ultra High Definition as it is officially called, delivers four times the resolution contained in the current standard of 1080p, approaching the maximum amount of video information resolved in a high-quality 35mm film print. The result is not only the potential for a staggering increase in detail, but also a smoother image and the complete elimination of the screen door effect visible when sitting closely to large HDTVs and PC monitors.

However, there has been much debate as to whether the jump to 4K is worthwhile, given that there are limits on how much detail the human eye can resolve in relation to smaller screen sizes - some experts claim that you'll need at least a massive 80-inch screen to really benefit from a noticeable increase in detail. Our own testing with 27-inch 2.5K displays revealed that there are tangible gains upgrading to a 1440p screen, and we imagine that in a similar desktop set-up the improvements in picture quality with 4K could be even bigger - as long as you don't sit too far away. In this respect, the typical desktop PC gaming scenario serves the new display standard quite well.

The Asus PQ321Q is one of the first desktop displays capable of displaying a full 3840x2160p signal at 60Hz, either via DisplayPort or using dual HDMI 1.4 connections. Up until now, previous 4K displays have been pegged at a mediocre 30Hz refresh, as we found in our first feature on gaming with the new ultra HD standard. At 32 inches the PQ321Q is well below the recommended screen size for use with 4K material, but the modest nature of the display does yield other advantages: sporting 140 pixels per inch (PPI), any hint of screen door effect should be practically invisible compared to 1080p at similar viewing distances, with the extra pixel fill leading to a tangible increase in image clarity.

1920x1080 (1080p) 2560x1440 3840x2160 (4K)

So what's the prize on offer here with the leap to 4K? While we can't really demonstrate pixel density advantages, we can show detail. Crysis 2 and its sequel feature some excellent artwork designed to scale up to the highest resolutions. Here you can see how 1080p and 2560x1440 compare to 4K. The difference is more pronounced in the Crysis 3 shot which generally has more contrast.

1920x1080 (1080p) 2560x1440 3840x2160 (4K)

So what's the prize on offer here with the leap to 4K? While we can't really demonstrate pixel density advantages, we can show detail. Crysis 2 and its sequel feature some excellent artwork designed to scale up to the highest resolutions. Here you can see how 1080p and 2560x1440 compare to 4K. The difference is more pronounced in the Crysis 3 shot which generally has more contrast.

Retailing at a whopping 3000, the PQ321Q is clearly a pioneering product aimed at the elite few, for whom money is no object. However, we understand that 4K display production is ramping up very quickly, and sub-$1000 products will be on the market within the year - therefore it's no surprise that both Nvidia and AMD are targeting 4K gaming for their top-end graphics cards. So this is something of a curious review then - we're covering a product you'll almost certainly never buy. In many ways, this is more of a preview - specifically, what to expect from 4K display technology, how it compares to the more established 1440p standard, and just whether that immense boost to detail is actually worthwhile.

First impressions

The PQ321Q clearly compares favourably with Dell's range of UltraSharp monitors in terms of overall aesthetic and functionality, with a sleek minimalist design that also allows for flexible positioning of the monitor. Build quality is generally excellent, and the display has a weighty feel to it. The PQ321Q comes complete with a stand that allows for full tilt, swivel and rotation of the screen, and there's also an option to wall-mount the monitor if you so desire.

However, the controls are located around the back of the display on the right side, so it's probably best to perform a full set-up sooner rather than later if you plan to take advantage of the wall-mounting option. Put simply, navigating through the menus is enormously difficult when you can't actually see the buttons and the screen at the same time, making set-up a highly frustrating experience. The position of the controls seems like a large oversight to make on a pioneering display like this one, and a cheap remote would have done wonders here without adding significant cost to the unit. As it stands you have to blindly feel your way around which makes adjusting various settings a real pain - something that's hard to accept for a mega-bucks display.

In terms of connectivity, there are two HDMI inputs and a solitary Display Port located on the left side of the unit. It is possible to output a 30Hz 4K signal using a single HDMI lead, but to get the full 60Hz experience you'll either need to use both HDMI inputs in a multiple monitor set-up, or to take advantage of the single Display Port connection instead. The slim form factor - just 1.4 inches deep - also houses a set of stereo speakers, accepting audio from the two HDMI ports. Sound quality is quite crisp and clear, but due to the thin size of the cabinet bass is sorely lacking with distortion coming into play at higher volumes. Audio support here is obviously something of an afterthought, with Asus seemingly presuming that you have a discrete audio system already in play.

Rather than opting for an IPS or VA panel, the PQ321Q is powered by an IGZO panel developed and manufactured by Sharp, featuring an edge-lit LED backlight. The advantage here is that by substituting the layer of amorphous silicon found in regular LCD panels with Indium Gallium Zinc Oxide (IGZO), transistors are smaller, resulting in more densely packed pixels that more quickly react to changes in electric current. This allows for massively high resolutions in small screen sizes while potentially providing a boost in motion resolution.

While the panel itself features a full 3840x2160 resolution, the PQ321Q is a tiled display, meaning that the screen displays two separate 1920x2160 images side-by-side in order to generate a full 4K picture. This explains how Asus has managed to break the 4K 30Hz barrier - by effectively running two lower bandwidth images side-by-side. Tiling is achieved via a single DisplayPort lead, but it does cause some problems - specifically extremely limited support for other resolutions in this Multi-Stream Transport mode. Indeed, even if MST is disabled and a standard dual-link DVI connection is used, support for staple resolutions like 2560x1440 appears to be absent, with 1080p just about the only other viable standard resolution.

"Just like HD before it, 4K adoption will be driven by video games support. However, running 4x1080p resolution at 60 frames per second requires a vast amount of GPU power - twin GTX 780s in SLI if you want to maintain high settings."

This library capture of Crysis 3 running on a six-core Intel PC with three GTX Titans in SLI highlights two of the major issues facing the 4K standard. First, the GPU power required to get a consistent experience is mammoth - certain effects cause frame-rate drops even with all this power - and secondly, the 30Hz upper limit on the existing HDMI 1.4 standard. HDMI 2.0 is coming but in the meantime, Asus used tiled displays - two 1920x2160 images side-by-side - to deliver 4K at 60Hz.

The utilisation of multi-screen tiling also means that picture stability is dictated by the quality of AMD and Nvidia's multi-display technologies. In the here and now, Nvidia takes the lead here owing to its "g-sync" tech it's brought across from its Quadro workstation GPUs - if you run a game without v-sync, the tear is consistent across the screen. AMD has issues it needs to resolve - specifically, lack of sync between the two images when v-sync is disengaged, resulting in some ugly issues. A fix is promised, but for now, we'd recommend limiting yourself to 30Hz and using a straight HDMI or DVI connection.

Display quality

Moving onto the quality is the display itself, the PQ321Q shares similarly attractive traits to Dell's range of IPS panels rather than marking a dramatic leap forward in LCD picture quality: viewing angles are generous with no overly noticeable colour or gamma shift when viewed moderately off axis, and greyscale and gamma tracking are excellent after calibration, resulting in a high degree of shadow detail, although the darkest parts of the image are crushed slightly - a common trait amongst LCD displays in general.

Additionally, we didn't notice any of the grey ghosting artifacts commonly found on VA type panels used by some manufacturers, with IGZO delivering IPS levels of performance, although motion handling is nothing special, with only around 300 lines of resolution clearly resolved - the same as most LCD screens. We also encountered some visible backlight clouding on test patterns and when viewing content in low light conditions. Your mileage may vary though, and if you receive one with patchy coverage you can always send it back as not fit for purpose and request another unit.



Elsewhere, colour accuracy is generally very good: skin tones appear natural across a range of different scenes, and the resulting picture appeared suitably vibrant without looking too overblown. In terms of meeting the Rec 709 HDTV standard, the colour gamut is slightly over-saturated where green and yellow is concerned though, and the knock-on effect on the other colours is that brighter reds appear discoloured, with some scenes taking on a slightly orangey-green hue. But generally speaking this is only a minor issue and won't be a problem for those who aren't used to seeing more accurate reference level displays.

Contrast performance is less impressive however, with poor black levels robbing dark scenes of considerable depth. With light output set at 120 cd/m2 (suitable for low light viewing environments) we measured black level at 0.1536 using an ANSI checker board pattern. In comparison, the best VA panels can achieve up to around 0.03 cd/m2 (Samsung C580 and Panasonic E6) that results in inky-looking blacks that approach plasma levels of performance. However, the PQ321Q does generate more light output than you'll ever need - a whopping 387 cd/m2 - making it well suited for use in well-lit rooms where the deficit in contrast performance is far less obvious.



The 4K revolution

The fundamental aspects of picture quality are very good on the PQ321Q, but what does the colossal increase in resolution bring to the table? Are we looking at a revelatory jump in detail, or do we need a bigger screen to really do the 4K format justice? In truth, the answer depends on just how close you sit from your display, but even from a few feet away on a 32-inch screen there are some clear and obvious benefits to be had from gaming at 4K. While there's no revelatory increase in detail, there is a visible jump in clarity and sharpness. The picture simply appears smoother and more natural, and less defined by the underlying pixel structure that is generating it. When gaming, text, logos and HUD elements appear super smooth and pin sharp, while the overall level of clarity across the scene is simply breathtaking.


Moving closer to distances more common when using a desktop PC monitor - in this case roughly two and a half screen heights away - and the differences between native 1080p and 4K become far more apparent. In titles that utilise extreme high resolution textures - such as Crysis 3 - the sheer amount of detail is staggering, with small nuances in the artwork fleshed out to a degree not seen when running the game at lower resolutions. Inevitably, not every aspect of a game's rendering pipeline will be geared towards such a high-resolution output, and the extra pixel precision can also bring to your attention some of the lower quality assets in use through some of today's most visually accomplished titles. The additional pixel fill also helps to lend a more three-dimensional look to normal mapped surfaces, and on the whole the increased level of clarity makes playing games more like looking through a window to another world than a finely constructed digital screen door. In that respect, the likes of BioShock Infinite and Tomb Raider are a joy to behold.

"In titles that utilise extreme high resolution textures - such as Crysis 3 - the sheer amount of detail is staggering, with small nuances in the artwork fleshed out to a degree not seen when running the game at lower display resolutions."

That said, image quality is still highly important when running games in 4K, and despite the small size of the pixels and the smooth-looking picture they generate, jaggies are still easily discernible on edges that lack anti-aliasing. Pixel-popping artifacts and shimmering caused by the bog-standard FXAA solution are both reduced over playing in 1080p on a native display, but not entirely. The use of low levels of MSAA benefits the image by smoothing over the more affected parts of the scene, but at 4K there's less of a need to excessively ramp up the use of multi-sampling if a game's post-process AA solution doesn't provide as much coverage as expected. MSAA is an absolute performance killer - especially so at 4K - and we fully expect improved post-processing techniques to replace it entirely.

In truth, it needs to. Take a look at our GTX Titan or GTX 780 reviews - both of which feature 4K benchmarks with everything maxed out. Ultra HD makes mincemeat of a typical benchmarking suite exactly because ramping up settings to the max utilises ever increasing amounts of the silicon for ever decreasing visual returns. MSAA is a part of that, but quality presets themselves are another. A single card struggles to get anything close to 30fps. Realistic anti-aliasing and quality settings could see you hit something approaching 60fps on older, or GPU-light games, but realistically you're looking at two high-end graphics cards running in parallel to deliver something approaching the complete experience - and even here, you should not expect to be running with high levels of multi-sampling.

We'll be running an article more closely focused on just what it takes to achieve 4K at 60fps soon, but in the meantime, we ran some quick benchmarks using two GTX 780s in SLI - our aim was to make the most of the 60Hz refresh and aim to get as close to full frame-rate gaming as we could. As you can see from the various runs, this requires compromise on quality, anti-aliasing - or both. Only BioShock Infinite and Tomb Raider could hit ultra settings and offer an average frame-rate close to 60fps, the key word there being "average". In truth to give a locked 60fps, you need a fair bit more leeway to ensure a consistent experience. Note how adjusting individual tweakables can result in mammoth performance gains - like Metro 2033's depth of field effect, for example.

"Hitting 60fps at 4K is a serious challenge, requiring realism on quality and AA presets and knowledge of the most GPU intensive effects per game. For example, Metro 2033's depth of field effect halves performance."

Nvidia GeForce GTX 780 3GB, 2x SLI, Average Frame-Rate at 3840x2160
BioShock Infinite, DX11 Ultra DDOF 54.9fps
BioShock Infinite, Very High 78.8fps
Tomb Raider, Ultra 62.9fps
Tomb Raider, High 104.8fps
Hitman Absolution, High, 2x MSAA 56.7fps
Hitman Absolution, High, FXAA 62.9fps
Metro 2033, High, AAA, DOF 38.0fps
Metro 2033, High, AAA, no DOF 77.0fps
Metro Last Light, High, High Tessellation, no SSAA 42.8fps
Metro Last Light, Medium, Normal Tessellation, no SSAA 55.0fps
Sleeping Dogs, High 61.1fps
Sleeping Dogs, Medium 114.6fps

In terms of gaming performance from a latency perspective, the ASUS PQ321Q also fares quite well in delivering reasonably fast and responsive sessions that didn't feel compromised by noticeable input lag. The level of responsiveness felt quite similar to that of Sony's PlayStation 3D Display when playing in 4K, which clocks in with a 33ms response time. While this will be a little too slow for pro gamers who play online, we had little trouble gunning down the residents of BioShock Infinite's Columbia, although control response in general felt a touch heavier than our reference Dell monitor.

Video processing

Ultra High Definition images look breathtaking on the PQ321Q, but with little in the way of 4K content available outside of PC gaming and short demonstration videos, the scaling of lower resolutions still plays an important part in the day-to-day use of any 4K display. Poor quality algorithms tend to heavily blur the picture resulting in a noticeable loss in sharpness and the amount of detail resolved on screen - not something we want to see happen to our extensive Blu-ray collection, or when running the most demanding PC games at 1080p in order to maintain a solid frame-rate that comes closer to the 60fps gold standard.


The good news is that the PQ321Q is fairly adept at scaling 1080p material without introducing too many artifacts on screen. Although the level of processing here is not to the same standards as found on some top-tier 4K HDTVs, it is definitely a class above standard PC monitor territory. The scaling solution on offer isn't perfect though: there is some visible ringing around objects and high frequency information also gets smoothed over to a degree, thus reducing the level of intricacy found in parts of the original 1080p signal. That said, Blu-rays appeared clear and smooth, with plenty of fine detail on show, while games such as Crysis 3 and BioShock Infinite remained crisp and well defined. Outside of a little fuzziness we never got the feeling that we weren't looking at a high definition picture, even though upscaled images do appear softer than when viewed natively on a 1080p display.

1080p 4K

Off-screen photos sadly don't do the display justice, but the PQ321Q does a very good job of scaling 1080p content to 4K without degrading picture quality too much. Other than a bit of fuzziness and reduction in high frequency detail, re-sized 1080p images appear reasonably sharp and still easily qualify as high definition.

1080p 4K

Off-screen photos sadly don't do the display justice, but the PQ321Q does a very good job of scaling 1080p content to 4K without degrading picture quality too much. Other than a bit of fuzziness and reduction in high frequency detail, re-sized 1080p images appear reasonably sharp and still easily qualify as high definition.

In other areas the PQ321Q's video processing is less impressive: 720p is poorly handled, with images suffering from excessive ringing, visible blur, and upscaling artifacts - though to be honest, the notion of running 720p content on a screen like this seems faintly ridiculous. 24p support for Blu-ray playback is also absent, meaning that films display judder during slow camera pans due to the 24fps signal being converted to 60fps, via the clumsy use of inserted duplicate frames. The PQ321Q is also unable to de-interlace 1080i material without introducing a loss of detail and additional jaggies compared to when handling 1080p signals, although we suspect that this won't be an issue for most people, given that 1080i is rarely used in the PC and gaming space.

Asus PQ321Q 4K display - the Digital Foundry verdict



The introduction of affordable 2.5K panels from South Korean manufacturers over the last couple of years - along with advancements in GPU technology - is already leading to 1080p being displaced in the high-end PC space, with 1440p setting the new standard for dual GPU gaming at a smooth 60fps. Retailing for around 300, we came away impressed with the Qnix QX271LED Evolution II and found it to be a highly attractive proposition for those who aren't willing to shell out a premium for a fully-fledged 4K display but who still want a tangible upgrade over their current 1080p screen. Once you've experienced 2.5K it's really difficult to go back to 1080p, and the increased pixel load is just about manageable on high-end games at decent settings even with a 200 graphics card - as long as you accept that a locked 60fps is off the table. Game developers are also comfortable with the 2.5K standard and will optimise around it. In the here and now, 2.5K is clearly the preferred pick for gaming beyond 1080p.

But ultimately, 4K is likely to become the new standard where enthusiast PC gaming is concerned, allowing for a leap beyond the next-generation consoles before they've hit the ground running. Our experience with the Asus PQ321Q shows that once the GPU rendering power - and proper developer support - catches up, gamers who embrace 4K are in for a treat. Just as 1080p didn't really cut it any more once we'd experienced what 2.5K had to offer, the new 4K standard manages to comprehensively beat that. A new console generation will be defined by the difference between 1080p and 720p, and with the arrival of 4K we are getting a preview of the next leap in visual fidelity. In a desktop environment, the difference is truly remarkable.

"2560x1440 currently offers the best value for taking the next step beyond 1080p, but 4K resolution is likely to become the new standard where enthusiast PC gaming is concerned."

However, the PQ321Q is clearly an experimental product with pricing to match. The tiling set-up is a fix put in place simply because the HDMI 2.0 standard wasn't in place when Asus put the display into production, and while it works fine in practice with Nvidia cards, it is still unwieldy. However, despite these concerns, Asus has still managed to put together a high quality Ultra HD display that can easily hold its own against the cheaper and more established 2.5K competition. While colour reproduction and black levels aren't as good as those on Dell's superb range of Ultra Sharp monitors - contrast ratio is poor in general for a 2013 display - the PQ321Q delivers stunningly clear and well balanced 4K images to the screen that immediately impress. The only downside is that use of the monitor in Windows can be challenging owing to poor DPI scaling and the sheer amount of pixels on offer here. It's simply too overwhelming.

Can we recommend this monitor for purchase? To be frank, the price of the screen and the knowledge that you're buying a display that probably won't support HDMI 2.0 (unless a future firmware update somehow enables it) does make it a bit of a non-starter. However, the fact that Nvidia and AMD are choosing to ramp up support for the standard strongly suggests that 4K will become a much bigger deal for gamers sooner rather than later.

For those with bottomless pockets looking to get an early experience of the next resolution standard for consumer displays, the Asus PQ321Q is a solid choice, featuring decent 1080p scaling, reasonably good colour accuracy, outstanding pixel pitch for 4K sources, and extremely generous viewing angles, all resulting in some superb-looking images. The reasonably low level of input lag also makes it a good around choice for gaming at both 1080p and 4K resolutions. Better, cheaper displays will come in time and the overall impression we were left with after our testing of the PQ321Q was that the wait will definitely be worth it.

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