Gaming Performance

The AOC U28G2XU2 sports a 144 Hz refresh rate IPS panel, which supports the adaptive synchronization technology from both AMD and NVIDIA graphics cards.

The adaptive synchronization range is 48–144 Hz, so that's the framerate range your PC should be able to achieve at 4K resolution to experience buttery smooth, screen-tear-free gameplay. The monitor carries the AMD FreeSync Premium badge, which means it supports the Low Framerate Compensation (LFC) technology. If the game runs at fewer frames per second than the bottom limit of the FreeSync operating range (48 FPS in this case), the LFC technology displays frames multiple times to stay above the lower limit of FreeSync and maintain the full fluidity of the action. Of course, this "multiplication of frames" is completely invisible to the human eye. Thanks to this approach, the bottom limit of the required number of frames per second become irrelevant and should not be thought about. But for the best possible gaming experience, a high framerate remains something you should strive for.

Response Time and Overdrive

The response time of the AOC U28G2XU2 is specified as 1 ms GtG. The panel uses overdrive technology to make the pixel transitions faster, and you will find the option under Game Setting > Overdrive in the OSD.

Overdrive has a total of five settings: Off, Weak, Medium, Strong, and Boost. The Boost option actually activates backlight strobing, so this isn't a real "overdrive" setting, rather just an attempt to max out the blur reduction capabilities of the AOC U28G2XU2. I don't recommend using it though, as it cranks the Motion Blur Reduction technology up to the highest available value (20) and drops the picture brightness down to 73 cd/m², which is far too low for most home users.

I tested the response time with the Open Source Response Time Tool Pro (OSRTT Pro), developed by Andrew McDonald of TechTeamGB. It's a nifty tool that, combined with the OSRTT Launcher app, measures panel response times and presents them through detailed graphs and easy-to-read heatmaps. You can find everything you might want to know about the OSRTT in its technical documentation and on the official website, where you can order your unit, too. The OSRTT Launcher gives us three interesting heat maps to observe.

Perceived Response Time tells us how much time the panel took to transition from one color to another. This measurement is expressed in milliseconds and includes overshoot. In other words, if the panel exceeded the target value, the perceived response time also includes the time it took for the transition to recover from overshoot and stabilize on the target value. I'm running my tests with recommended settings, so with a fixed RGB 5 tolerance level and with gamma-corrected RGB values.

RGB Overshoot tells us how much a specific transition missed the target value. For example, if the panel was transitioning from RGB 51 to RGB 204, and it initially landed on RGB 212, the overshoot RGB value is 8. Overshoot can be both positive and negative, and it commonly occurs at extreme overdrive settings when pixels are driven by high voltage. In practice, an overshoot manifests as an afterimage or a halo around a moving object. It can be easily spotted even when doing something as basic as scrolling through a webpage.

Visual Response Rating is the most abstract heatmap generated by the OSRTT Launcher; in essence, it's an ever-evolving scoring system. To quote OSRTT's technical documentation, it is a finite score rather than a direct measurement. The calculation is pretty simple; it's: "100 – (Initial Response Time + Perceived Response Time)". Since both metrics use the same tolerance level, if a display doesn't overshoot, both times will be identical. This essentially rewards displays that are fast with a small amount of overshoot over displays that aren't as fast even if they don't overshoot at all – while still overall preferring ultra-fast, accurate monitors.

Here's how the AOC U28G2XU2 fares in the pixel response time test for all four "real" overdrive settings: Off, Weak, Medium, and Strong.






After examining the results, the best option is to leave the Overdrive setting at Off. As you can see in my results, it yields the lowest perceived response time of 4.78 ms and has the least amount of overshoot, although it's surprising that the overshoot is present at all. There's not a single overdrive setting where moving objects don't have any overshoot at all, but at least the anomaly is very hard to spot when Overdrive is set to Off. This is apparently an inherent characteristic of the Innolux M280DCA-E7B IPS panel used by the AOC U28G2XU2, as well as its direct competitors.

Moving Picture Response Time (MPRT)

In the OSD is the MPRT slider, hidden under the MBR (Motion Blur Reduction) name. It has an adjustment range spanning from 0 to 20; MBR is deactivated when set to 0, but as soon as you set it to 1 or anything higher, the backlight starts strobing in order to reduce the perceived motion blur. The higher the number, the faster it strobes, and with that comes a reduction in actual picture brightness. It drops to 200 cd/m² with the MBR slider set to 1 and then progressively goes all the way down to 73 cd/m² when MBR is set to 20.

The ability to manually adjust the MBR level is interesting, as it allows you to find a good compromise between motion blur reduction and acceptable picture brightness. I wouldn't push it past 10 (141 cd/m²), but there's certainly room for experimentation in the 1-10 range, where there's no significant visible overshoot or strobe crosstalk present. Ultimately, though, I'd avoid using MBR altogether and rather enjoy the full brightness range of the monitor, which isn't that great to begin with.

Input Lag

To measure the input lag of a monitor, I switched from using the LDAT V2 (Latency Display Analysis Tool), which I've covered extensively in my NVIDIA Reflex review, to the OSRTT Pro Tool. The OSRTT Pro Tool and the accompanying software include a DirectX code developed by Andrew McDonald of TechTeamGB, which allows the OSRTT Launcher to track the events and capture the frame time, making it possible to isolate the monitor latency from other factors that come into play when using the click-to-photon testing methodology, namely the USB polling rate and game render time. For a deeper insight, I suggest you watch an excellent overview video made by Andy himself.

While I used a consistent methodology in all my previous LDAT-based monitor reviews and kept everything the same, switching to the OSRTT-based approach isolates me from potential issues, such as game engine updates (I based my tests on Overwatch, which transformed into Overwatch 2), and allows me to move on to a different testing system at will. I have to admit it was becoming increasingly annoying having to keep my old Core i9-9900K/RTX 2080 SUPER test system around for nothing but monitor input lag testing. Thanks to Andy for his tireless work on the OSRTT Tool and the OSRTT Launcher software!

Here's how the AOC U28G2XU2 holds up in terms of input lag after doing 100 iterations of the input lag test.


The AOC U28G2XU2 shows an average input lag of around 3.1 milliseconds, which is an excellent result for a gaming monitor. Such low input lag can't be picked up even by the most hardcore gamers, including esports professionals.


It's worth noting that the AOC U28G2XU2 offers a Low Input Lag option in the OSD (Game Setting > Low Input Lag). If you turn it off, the average input lag jumps up to 9.6 ms. I didn't notice any drawbacks of having the Low Input Lag set to On (the manual refers to the toggle with an ambiguous "Turn off frame buffer to decrease input lag"), so I suggest you keep it on.