AOC U27G4R Review – 4K 160Hz AND 1080p 320Hz IN ONE MONITOR! 

Have you ever wanted a fast 4K monitor for a visually stunning game like Cyberpunk, but also an ultra high refresh rate 1080p monitor for esports? Well, amazingly, this BOTH! This is the AOC U27G4R, a 4K 160 hertz IPS gaming monitor, that can be swapped to run at 1080p and 320 hertz! This thing sounds like a dream, so let’s test it out and see just how perfect it is – or isn’t! We’ll start with a little tour, where at least from the back you get a rather nice view. AOC have modified their styling just a little, with a nice sharp angled design molded into the plastic backing, with the red accents making a comeback. Since we’re back here I should mention the IO, which is split into two areas – one down at the bottom with two HDMI ports, one DisplayPort, a USB 3 downlink port and a yellow charging Type A port, and the other on the side with a further three USB A ports available. Annoyingly, despite this being a pretty fancy monitor, AOC hasn’t opted to use a nice joystick style switch to control the on screen menu, instead opting for the old school separated buttons that hurt your wrist to operate. 

Luckily the menu itself is nicely sized and reasonably well laid out, although I’d argue they are missing a few submenus here, as things like the colour controls are all laid out, and options like HDR are buried under what feels like a hundred individual colour controls. Happily the most important setting is at the top – the dual frame rate mode. You weirdly have three options here, 4K 120, 4K 160, or 1080p 320. I’m guessing the 4K 120 is for HDMI but it’s greyed out when using DisplayPort so who knows. It’s kind of a shame that they don’t seem to offer a hotkey option to chop and change between these modes. The other setting you’ll want to fiddle with is likely the overdrive settings, which again are hidden away under a mountain of other options. In here though you have four total modes, and of course they set it to “Normal” (AKA off) by default… We’ll come back to these in a minute though. 

Looking at the display from the front, you’ve got a reasonably thick (and branded) chin bar, a fairly sleek stand, and reasonably thin bezels. The stand has an almost diamond-shaped foot, and is otherwise pretty stable and maneuverable. You’ve got height adjust, tilt and swivel, and even rotation into portrait mode, should you want it. One thing you might notice though is that the foot isn’t weighty enough to let you swivel the monitor without it just turning the whole thing, so you’ll need to hold it to adjust, but I don’t know how many people adjust their monitor with any amount of regularity so it’s hardly a big deal. 

On the face of it, the panel looks pretty nice. With 400 nits of peak brightness and a nice vibrance to the colours, it’s a pretty decent content consumption display – at least at 4K anyway! Naturally I put those colours to the test, and in the 4K mode you get 93% coverage of the DCI P3 spectrum, or 68% of Rec2020. That’s decent, although a little low. A really good result here is 100% DCI P3 and over 80% of Rec2020, so this is good, but not amazing. Brightness is just shy of 400 nits, basically a 1000:1 contrast ratio, and an averaged DeltaE of 2.1, which is again decent but not perfect. I did also test in the 1080p mode to see if that makes any differences, and it really didn’t change much. It’s still the same colour gamut coverage, still just shy of 400 nits, and still around 2.1 DeltaE average. That’s good at least!

What does change is the response times – quite a bit actually! In the 4K 160 mode, the normal overdrive mode (which is stock, as is the 4K mode) came in at 5 milliseconds on average, which is actually pretty good considering the refresh rate window at 6.25 milliseconds. That’s around 200Hz equivalent, so we’re already off to a good start. The next mode, “Fast”, improves by half a millisecond on average with functionally no overshoot to speak of, so that’s a great sign too, and means that 83% of the transitions are within the refresh rate window which is great. On the next mode up, “Faster”, we start to see some more notable overshoot – although an initial response time of just 3.55 milliseconds. It’s still pretty manageable though, and not overly visible to the eye – for context here is what “Fast” and “Faster” look like at 4K 160 in slow motion. There’s not that much of a difference between them to the eye, so “Faster” seems like a good option. The next mode up though, “Fastest”, is just ridiculous. While the initial response time does fall to just 2.76 milliseconds, the perceived time actually goes up above the refresh rate at 7.3 milliseconds, and that’s obvious to the eye. The overshoot is unmanageable here, so no, do not use this mode. Stick with “Faster” and you’ll have a great time.

When you switch to the 1080p mode though, there are a few changes. Normal is functionally the same so we’ll skip over that, and fast is practically the same too, only without any overshoot at all, unlike the 4K mode which had a couple results 1 or 2 RGB values above or below the target, but “Faster” has significantly less overshoot, albeit running slightly slower at 3.8 milliseconds on average rather than 3.55, and “Fastest” also offers significantly less overshoot – an average error or 10.5 RGB values instead of 22.7! It’s still kind of unusably bad, but it’s notably better than at 4K. One thing to note is that at 1080p 320, unless you use the horrendous overshoot mode, the average initial response time doesn’t fall within the refresh rate window at all, but the perceived time on that mode doesn’t fit in either so effectively this cannot adequately run at 320 hertz – at least without multi-frame ghosting. On “Faster” it runs at 262 hertz equivalent, which is pretty close, but it isn’t exactly there – and it’s no OLED. 

I can say though that the input lag in both modes is spot on – and this does help demonstrate why a higher refresh rate is useful. At 160 hertz you are waiting, on average, around 3 milliseconds for a new frame (that’s half the refresh rate). At 320 hertz you’re waiting 1.5 milliseconds or so. It isn’t much, and the higher the refresh rate, the more diminishing returns you get, but it’s still an advantage to go along with the smoothness. But of course the real question is: is it any good for gaming? The short answer is: yeah, kinda. The longer answer, well that’s a little more nuanced. At 1080p320 it’s obviously smooth and fast, although it’s noticeably grainy. I’ve never liked 1080p at 27 inches, and this is no different. It’s just doing a straight 1 to 4 copy, so it sure does look like a 1080p 27 inch display. The panel too isn’t quite up to the task, with a little bit of ghosting between frames. I’m very much used to gaming on an OLED now, so to go back to an LCD panel can be a little more jarring than you might expect. With that said, it is still a pretty smooth and responsive experience, and of course running at 1080p means at least in esports type games you are likely to get that kind of FPS to match. 

Then when you flick the setting and swap to a more visually impressive game – I opted for Dirt Rally 2.0 here, a brilliant game – and chill with a controller and some dreadful driving, it’s amazing. It’s sharp, still plenty smooth and a slightly better experience thanks to undercranking the refresh rate (at least by comparison anyway). It’s great, the colours pop nicely, and feels just as immersive as you’d expect. The thing you might want to consider though are 1440p displays. Most people settle on 1440p as it’s an excellent middle-ground between 1080p and 4K in terms of sharpness and clarity, and performance, and they don’t require you to switch modes to enjoy either a smooth or sharp experience. Personally, I still think that’s a better fit for me. With that said, this U27G4R is only £300, and if you look at it more as a 4K 160Hz FastIPS gaming monitor that has an extra party-trick feature of being able to double the refresh rate at a quarter of the pixel count, then I don’t know why you’d buy any other 4K high refresh rate LCD. Unless you’re spending an order of magnitude more money, you’ll struggle to get something better, and with such a neat feature, it’s really hard to argue this isn’t an exceptional choice. Sure, it isn’t perfect, and I still think I’d prefer a 1440p high refresh rate panel instead, but still.