Most 4K panels max out at 144 Hz, but the GP27U and the standout of the comparison group, Samsung’s G8, go higher. The remaining panels are Dough’s Spectrum D03 Glossy, ViewSonic’s XG321UG, Philips’ 279M1RV and Corsair’s 32UHD144. The Cooler Master, ViewSonic and Samsung are Mini LED panels, while the rest employ edge backlights.
Pixel Response and Input Lag
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The GP27U is officially the quickest 4K monitor I’ve yet tested, beating even the stellar Samsung G8 by 2ms. Though the Samsung monitor’s 240 Hz refresh rate gives it a faster draw time, the Cooler Master has extremely low input lag, making up the difference. My gaming skills are insufficient to see a difference while playing, and the Samsung looks smoother when running over 200fps. But professional-level gamers may gain an advantage from the GP27U’s lower lag. It’s quick, and if you can push the pixels faster than 120fps, it’s an excellent experience. Note that I tested the GP27U at 160 Hz, so I couldn’t use Adaptive-Sync. Even at 160fps, I could see a few frame tears. The monitor provides the most balanced performance when running at 144 Hz.
Viewing Angles
The GP27U’s viewing angles are comparable to any premium IPS panel found today. Light output is unchanged at 45 degrees to the sides, and there is a slight color shift to green. Shadow detail remains clear. The vertical plane shows a blue tint, but detail is less washed out than most panels.
Screen Uniformity
To learn how we measure screen uniformity, click here.
My GP27U sample aced the uniformity test with a super-low 2.44% deviation from the center zone. I thought that might be a record, but scanning my test database of 326 monitors revealed that honor belongs to the Asus PA32UCG. Any score under 10% realistically means no visible hotspots, bleed or glow. And I’ve measured a good number of screens under 5%. But this is impressive nonetheless, especially considering the Asus’ price of over $3,000.
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