Gaming Performance

The Viotek GFV27DAB sports a native 165 Hz refresh rate VA panel, meaning 165 Hz mode doesn't have to be "unlocked" in the OSD by overclocking the panel. It is available out of the box and works perfectly on every existing sample of the GFV27DAB.

The panel supports the adaptive synchronization technology for both AMD and NVIDIA graphics cards. The adaptive synchronization range is 48–165 Hz, so that's the framerate range your PC should be able to achieve at QHD resolution for you to experience the buttery smooth, tear-free gameplay. While Viotek doesn't mention the AMD FreeSync Premium certification in any of their materials, the monitor does support the Low Framerate Compensation (LFC) technology, which comes with the FreeSync Premium branding. If the game runs at a lower number of 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 becomes irrelevant and should not be thought about. Of course, for the best-possible gaming experience, a high framerate remains something you should strive for.


The monitor offers a set of gaming-oriented features, combined under "Game Plus" in the OSD. Here, you'll find a countdown timer (15, 30, 45, 60, or 90 minutes), FPS counter, and three types of virtual crosshairs in green and red.

Response Time and Overdrive

The Viotek GFV27DAB has a specified 1 ms response time. The panel uses overdrive technology to make pixel transitions faster, and you will find the option under the name "Overdrive" in the OSD (Main Menu > Gaming Setup > Overdrive). Overdrive has a total of four settings: Off, Low, Middle, and High.


I extensively tested all of them by using the so-called pursuit camera method developed by the good people of Blur Busters, namely Mark D. Rejhon. The idea of the procedure is to use a standard DSRL camera to capture the motion blur exactly like your eyes see it. That's achieved by mounting the camera on a smooth slider, setting the camera exposure to four times the length of the monitor refresh rate, and loading the Ghosting Test Pattern with the Pursuit Camera Sync Track invented by Mark Rejhon of Blur Busters. The camera then has to be slid sideways at the same speed as on-screen motion. The sync track is there to tell you if you're moving the camera too fast or too slow, or if it shakes too much. The procedure takes some practice and getting used to, but yields great results and lets us examine the differences between various Overdrive settings at various monitor refresh rates.

I made a series of photos at 60, 100, 120, 144, and 165 Hz, with all five available Response Time settings. Let's look at the results and figure out what the ideal Overdrive setting would be.



Assuming your PC is powerful enough to constantly run your games at 120 or more FPS at 2,560x1,440 resolution, I'd recommend setting Overdrive to Low or Medium for the best overall experience. If your framerate is regularly dropping below 100 FPS or is not even reached, meaning you're highly dependent on the adaptive synchronization technology to smooth out the gaming experience, you should set Overdrive to Off. It's a shame that there isn't a single, universal Overdrive setting that works best for all cases, but hey, that's one of the purposes of reviews like this one.

Moving Picture Response Time (MPRT) Performance

In the OSD (Main Menu > Gaming Setup), the Viotek GFV27DAB offers the MPRT toggle. If you turn it on, the backlight will start strobing to achieve a "1 millisecond-like" response time at the expense of picture brightness and other strobing-related issues, such as flickering and strobe crosstalk. The "1 ms MPRT" response time is not to be confused with 1 ms GtG response time, as the commonly used GtG value tells us how much time it takes for a pixel to change between two colors, while MPRT, also known as display persistence, represents how long a pixel is continuously visible. Important to know is that MPRT isn't a blur reduction technology, but a measurement, which can be lowered by backlight strobing.

The MPRT technology can be activated even when the panel is set to the 165 Hz refresh rate, but in Viotek's implementation, it is not compatible with the adaptive synchronization. In other words, it's either MPRT or FreeSync/G-SYNC (or neither).

Here's a comparison of moving object sharpness with the MPRT toggle off and on, both recorded at 165 Hz.



Activating MPRT results in the sharpest possible moving visuals the Viotek GFV27DAB has to offer, but it comes at a heavy price: the brightness of the panel drops to 109.22 cd/m², and there's no way to increase it. As soon as you touch the brightness setting in the OSD, the MPRT technology simply turns off. For this reason, and because apparent strobe crosstalk is present, it's best to forget about MPRT. It makes the screen too dim to be comfortably used, especially in daytime.

Input Lag

To measure the input lag of a monitor, I switched from using the high-speed camera method to a new tool: the NVIDIA LDAT v2, which I've covered extensively in my NVIDIA Reflex review.

The Latency Display Analysis Tool (LDAT) is a small device that is strapped to a monitor to measure brightness changes, and it provides us with end-to-end system latency data—the so-called mouse to photon latency. Using it for reliable and repeatable monitor input lag testing was made possible by NVIDIA's inclusion of the flash indicator feature in some Reflex-supported games. The flash indicator is essentially a white box displayed at the left edge of the screen when a mouse click "arrives" on the screen. I simply place the LDAT sensor on the part of the screen where the flash indicator will appear and click the mouse button on the sensor itself. The sensor will then detect the sudden change in brightness and calculate how much time has passed between the mouse button click and flash appearing on the screen—that's the aforementioned end-to-end system latency. While this method doesn't let me isolate the input lag of the monitor as the only measured value, which the high-speed camera method didn't either, if the rest of my system remains unchanged, tested monitors can be compared to each other.

One other excellent characteristic of the LDAT method is the Auto Fire feature of the LDAT software. The Auto Fire feature allows me to select a number of "shots" (test iterations), as well as the "shot delay" (a delay between mouse clicks). All I have to do is run the desired game, align the LDAT sensor to the flash indicator area, and press the "mouse" button on the LDAT. The sensor and accompanying software take care of everything else. Less than a minute later, I have my test results—the minimum, average, and maximum measured end-to-end system latency and standard deviation.

The game I'm using for monitor input lag testing is Overwatch, for several reasons. It has an integrated 400 FPS framerate limit, which my test system has no trouble hitting and maintaining at low settings at any given resolution. By keeping the framerate at 400 FPS, I'm maintaining a low and constant GPU render latency of around 2 ms. Overwatch also has an easily accessible practice range, which allows me to do all of my tests in a controlled environment. Finally, its game engine detects inputs even when a gun is reloading, meaning I don't have to worry about character selection or their ammo magazine size—once I trigger the Auto Fire feature, the test will run in 100 iterations regardless of what's happening in the game. My tests are conducted with the NVIDIA Reflex technology turned off (at 400 FPS, it wouldn't make any difference to system latency anyway), with any adaptive refresh rate technologies (G-Sync, FreeSync, and VRR) deactivated and V-Sync off.


In the end, we get the so-called button-to-pixel lag—the time that passes between doing an action with the mouse and said action first registering on screen. Anything below 16 ms, which equals one frame of lag at 60 Hz, can be considered gaming-grade, and such a monitor is suitable even for most demanding gamers and esports professionals. If the input lag falls between 16–32 ms, which is between 1–2 frames of lag at 60 Hz, the monitor is suitable for almost everyone but the most hardcore gamers, especially if they're playing first-person shooters on a professional level. Finally, if a monitor's input lag is higher than 32 ms, which is over 2 frames of lag at 60 Hz, even casual gamers should be able to notice it. Will they be bothered by it? Not necessarily, but I can't recommend a screen like that for serious gaming.

Here's how the Viotek GFV27DAB holds up in terms of input lag.



After 100 iterations of the LDAT-powered input lag test, the Viotek GFV27DAB showed an average input lag of only 11.1 milliseconds, which means it's responsive enough even for most demanding gamers. Great stuff!