AORUS FO48U 4K 120Hz OLED Review – AMAZING, on paper…

On paper, the Aorus FO48U is possibly the best display you can buy right now. It offers 48 inches of 4K 120Hz OLED glory with 10 bit colour, instant response times and even genuinely impressive speakers built in, but there’s a catch. Actually there are quite a few, enough that I went from being incredibly excited to have this in to test, to being somewhat put off from using this at all. There is a whole lot to unpack here, so strap in because this is gonna be a long one!

Let’s start off with the specs, because like I said, on paper this looks to be one of the best displays on the market right now. It’s a 48” 3840×2160 120Hz OLED. It sports two HDMI 2.1 ports – sadly they only run at 24Gbps not the full speed 48GBps – alongside a DisplayPort 1.4 port and a USB C port that supports DisplayPort Alt mode and even Display Stream Compression (DSC). That USB C port also means, in combination with the 2 port USB 3 hub, this has a KVM built in meaning you can hook up your keyboard and mouse and have the display switch which system they are connected to when it switches the display inputs.

Again, on paper the 95% coverage of the DCI-P3 spectrum should lead to an exceptional viewing experience, of course coupled with the infinite contrast ratio offered by the fact each pixel can just outright switch off to display black. Content can look absolutely stunning here – just look at that juicy steak bouncing on the grille! Or this fire in the woods. Beautiful.

Unfortunately, once you start looking at brighter content – especially anything that is trying to display white across more than just a few pixels at a time – you start to very clearly see the limitations. These jelly sweets bouncing in the water are meant to be dropping onto a bright white background, but here it’s very much grey. In fact, I’ll superimpose half of the same frame on screen with the actual content so you can see a side-by-side comparison of what it should look like, and what it actually looks like. The white of the original clip becomes a mid-grey, and makes the viewing experience pretty lacklustre.

The reason for this isn’t that the OLED is incapable of displaying white, no it’s mostly thanks to the Adaptive Brightness Limiter “feature” that this, and the LG C1 OLED that shares the same panel both use. Frustratingly, Gigabyte’s approach here seems much more aggressive than LG’s, and you cannot disable this at all. Every picture mode, every option, everything you can think of, it still happens. And, when I say it’s aggressive, this is what I mean. When you have a small bright window it can be plenty bright – upwards of 400 nits or higher depending on its size – but as the window grows the brightness of the whole panel dimms. Just look at the galaxy background, see how much less you can see when the explorer window is almost fullscreen? It’s a significant difference, and worse it’s not all that fast either. That means for bright transitions it will actually output a hefty amount of light… for about 50 milliseconds…

You can see that on this response time graph, where it jumps to 42% brighter then slower trails back down to the “resting” level. It takes more than 200 milliseconds to actually come to a rest, meaning that flash is sustained and is incredibly visible to the eye and really distracting. It actually gets worse depending on what colour precedes the bright shade – the one I just showed was RGB 153 to 204 ( a pretty small transition from ‘fairly bright’ to ‘a bit brighter’ ) but this is from RGB 0, or full black, to RGB 255, which should be full white. The reason you are seeing a flat line here is because the panel far exceeds the brightness my OSRTT unit was expecting so is literally clipping over the top. This is easily 50% brighter if not more, meaning a dark to light transition, say in a game or film, is visually difficult to watch.

This limitation also means that the gamma curve – the balance of light to RGB values to better match how our eyes perceive brightness and colour – is way, way off. The on-screen menu does have specific gamma options ranging from 1.8 to 2.6, but they are all utterly useless. Here’s what I measured the gamma 2.2 curve to look like – red is the actual data and green is what gamma 2.2 should actually look like. See the problem here? Anything above RGB 153 – just 60% of the colour space – is functionally identical. That makes for a poor viewing experience for sure.

It’s worth noting that the menu also has options for contrast – a related feature to gamma – in fact it has three. In the “Picture” menu you have “Contrast”… And “Advanced Contrast”… then if you go to the “Gaming” menu you have the “Black Equaliser” option which as best as I can tell just changes the contrast. And these are all competing…

Since I mentioned response times, it’s worth talking about them specifically. Of course, being an OLED panel the initial response time is near instant – right around 1ms or less. The problem here is the weird stuff it does – like overshooting to the moon and back as I mentioned, but also undershooting like crazy. Here is another graph, this time showing the same RGB 204 and 153, but this time it’s going from the brighter shade to the darker shade. See that? That’s dropping to something like RGB 110, or around 43% of the light level. FOR AN ENTIRE 8MS FRAME! It does the same thing from RGB 255 to 204, again for a full frame.

When it comes to actually gaming on it, it’s definitely more manageable than the test results would have you believe, although it’s still definitely one of the less enjoyable gaming experiences I’ve had. Of course the instant response times – even if it fancies overshooting like crazy for entire frames – make it pretty snappy. The issues with brightness and contrast can make it really difficult to strike a balance between being able to see in brighter areas and not having any shadowed spots be practically pitch black. For competitive games where you can ‘optimise’ for the darker areas and sacrifice a blown-out skybox, that’s fine, although for something a little more visual-driven it can be less ideal.

Interestingly, on the note of motion clarity, the panel does support backlight strobing via their “Aim Stabilizer” mode – which can only be enabled when you are running at over 100Hz and with Freesync disabled. With it on, it strobes the panel off and on I think around 2000 times per second. This is rather different to the more standard strobing modes that opt to just turn the display off for all bar 1ms on each frame, although thanks to the actual instant response times you do get a much smoother experience even if I still get headaches from this sort of flickering.

When it comes to the colours, I’ve mentioned a few of the issues so far including its inability to display white on any more than a small portion of the screen, but it actually gets worse. While it will happily cover 94% of the DCI-P3 spectrum in terms of gamut coverage, the accuracy is, in a word, atrocious. You can expect an average out-of-the-box DeltaE of over 10 in its “Standard” picture more, or worse more like 11.5 in the sRGB mode. And that’s on top of the peak 130 nits or so of full-screen peak brightness. In smaller windows I saw up to 400 nits, and in theory in HDR and with a tiny 2% window it can hit up to 800 nits, but for a lot of content the best you can expect is between 100 and maybe 200 nits.

It’s worth noting that this is an RGBW pixel layout too which means text and fine details often look just a bit off – take the text on Youtube, it has a noticeable green tinge on the back and looks just a touch “unsharp”, especially compared to a conventional pixel layout, at least in Windows. It’s also interesting to look at what the pixels are doing here, as even on bright white it won’t use all four colours. It refused to light the red sub-pixels to mix with the white, blue and green, even on the fairly warm “Normal” profile.

Since we are talking about the pixels, let’s talk burn-in. It’s arguably one of the biggest concerns most people have with OLEDs, and one of the areas where I think there is the most development, especially in the post-production space. Things like the automatic brightness limiter, the pixel shifting that isn’t present here, and the wear levelling that is, are all there to try and extend the lifespan of the panel and ensure burn-in doesn’t happen.

Sadly, despite the menu listing the panel’s current lifetime usage as just 280 hours, my unit already has burn-in. The Windows taskbar – specifically the shadow it casts on windows above it – and some random file icons on the desktop from the previous reviewer or sales person are burned in and visible on mostly uniform backgrounds. Sure, most of the time you won’t notice that, but the fact that at just 280 hours of usage it’s already got this level of wear is concerning. That also lines up with the experience Wendell talked about in an LTT video last year with his LG CX OLED.

Which I think brings us nicely on the competition. While of course there are plenty of “conventional” LCD based options like the Acer CG437KS I reviewed fairly recently, or even the Philips Momentum 55, those have their own problems like horrifically slow response times thanks to slow VA panels, so let’s stick with OLEDs. The LG C1 OLED I’ve mentioned throughout this video, the one that I believe shares the same actual panel as this one, can be had for £400 LESS than this, for arguably a better display with full-bandwidth HDMI 2.1 ports, admittedly no DisplayPort 1.4 or USB C KVMs, but with a better overall usage experience for sure. Alternatively, you can pick up the brand new, next generation, LG C2 48” OLED for around £250 less than this too. And, like, why wouldn’t you?

I really wanted to love the FO48U, I really did. I specifically requested this sample from Gigabyte because I really wanted to try it out, but.. Well… I’m not angry, I’m just disappointed. Sure in the right conditions this can be a visually stunning panel, and a snappy gaming experience, but it didn’t take much to make it a far from perfect experience instead. A single bright scene burning your retinas for 50 milliseconds then being too dim to distinguish 40% of the entire RGB range is not a fun experience, and not one I’d want to pay considerably more for over the competition for.