AOC CQ27G4ZH Gaming Monitor Review: 300 Hz For Less Than You’d Expect

This is a 27-inch curved VA QHD gaming monitor featuring 300 Hz, Adaptive-Sync, HDR10, and a wide gamut color range.

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AOC CQ27G4ZH
Editor's Choice
(Image: © Tom's Hardware)

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Our HDR benchmarking uses Portrait Displays’ Calman software. To learn about our HDR testing, see our breakdown of how we test PC monitors.

The CQ27G4ZH supports HDR10 signals with four separate picture modes. Three of them are also available as emulations for SDR content. There is no dimming available but since native contrast is so high, that omission can be forgiven here.

HDR Brightness and Contrast

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AOC CQ27G4ZH
(Image credit: Tom's Hardware)

If ultimate brightness is your goal, Mini LED is the only game in town. The Xiaomi has an HDR1000 certification, and it is extremely bright when showing HDR content. The CQ27G4ZH is a bit lower than the rest but its forte lies at the other end of the spectrum. Black levels are incredibly low to where it achieves almost four times the contrast of the next best screen without any dimming required. High native contrast is what makes OLEDs so good, and it makes VA a great technology for low priced HDR monitors. This is excellent performance.

Grayscale, EOTF and Color

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AOC CQ27G4ZH
(Image credit: Portrait Displays Calman)

You can’t calibrate the CQ27G4ZH in HDR mode, but it comes close to the mark in my color tests. Grayscale runs a bit cool in tone, but the EOTF is about as close to perfect as I’ve seen from any HDR monitor at any price. The measured values are super close to the reference line with only a soft transition to tone mapping on an otherwise superlative chart.

In the gamut tests, we can see most points are close to their targets with a little undersaturation in green and cyan, and slight oversaturation in blue. Magenta, blue and cyan are off hue as well. These are minor errors when compared to HDR monitors. The BT.2020 test shows 85% coverage of red, 65% green and 100% of blue with a similar hue error. The CQ27G4ZH’s HDR color is very good and there is no cause for complaint.

Test Takeaway: The CQ27G4ZH doesn’t offer dimming to increase HDR contrast but with a native ratio over 5,600:1, that is entirely forgivable. It isn’t super bright but low black levels make up for this and create a deeply textured HDR image with crisp detail and accurate color. Compared to other budget HDR screens, the CQ27G4ZH looks really good.

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Christian Eberle
Christian Eberle
Contributing Editor

Christian Eberle is a Contributing Editor for Tom's Hardware US. He's a veteran reviewer of A/V equipment, specializing in monitors. Christian began his obsession with tech when he built his first PC in 1991, a 286 running DOS 3.0 at a blazing 12MHz. In 2006, he undertook training from the Imaging Science Foundation in video calibration and testing and thus started a passion for precise imaging that persists to this day. He is also a professional musician with a degree from the New England Conservatory as a classical bassoonist which he used to good effect as a performer with the West Point Army Band from 1987 to 2013. He enjoys watching movies and listening to high-end audio in his custom-built home theater and can be seen riding trails near his home on a race-ready ICE VTX recumbent trike. Christian enjoys the endless summer in Florida where he lives with his wife and Chihuahua and plays with orchestras around the state.