Results: Pixel Response And Input Lag
To perform these tests, we use a high-speed camera that shoots at 1000 frames per second. Analyzing the video frame-by-frame allows us to observe the exact time it takes to go from a zero-percent signal to a 100% white field.
The pattern generator is placed at the base of the monitor so our camera can capture the precise moment its front-panel LED lights up, indicating that a video signal is being received by the monitor. With this camera placement, we can easily see how long it takes to fully display a pattern after pressing the button on the generator’s remote. This testing methodology allows for accurate and repeatable results when comparing panels.
Here’s a shot of our test setup. Click on the photo to enlarge.
The brighter section of the camera’s screen is what actually appears in the video. You can see the lights of the pattern generator in the bottom of the viewfinder. We flash the pattern on and off five times and average the results.
Here’s the screen draw result.
A 25-millisecond result is just what we’d expect from an IPS screen. Even though IGZO technology has the potential to improve on this aspect of performance, we believe the display’s electronics are the limiting factor. Moving almost 8.3 million pixels requires a lot of bandwidth and it’s going to take time for all the different components to catch up.
Here are the lag results.
If high-speed gaming is your primary reason for buying a 4K screen, Asus' PQ321Q is the better choice right now. For those with super-fast reaction times, you would be better served by a TN-based display equipped with G-Sync, or some other display with a 120 or 144 Hz refresh. Asus and Dell are marketing these as professional-, rather than enthusiast-oriented products. Dell takes that a step further with its selectable color gamuts and precise accuracy. As we’ve stated before, 4K gaming requires two things right now: big compromises and a pile of cash.