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The 27GX790A features 13 picture modes, each with a distinct interpretation of color, gamma, and grayscale tracking. I used the default Gamer 1 and sRGB modes for the benchmark tests.
Grayscale and Gamma Tracking
Our grayscale and gamma tests use Calman calibration software from Portrait Displays. We describe our grayscale and gamma tests in detail here.
The default grayscale tracks a bit warmly, with red errors visible above 20% brightness. This is more forgivable than green or blue, which are more obvious to see. However, it will slightly dull the image. Gamma tracks almost perfectly just above the reference line.
Calibration reduces all errors below the visible threshold. Gamma is slightly but not visibly affected. This is very good performance.
Grayscale in sRGB mode is even warmer by default, but unlike many monitors, it can be tweaked to a higher standard using the RGB sliders. Gamma tracks slightly dark and cannot be adjusted.
Comparisons
The 27GX790A comes last with a 5.70dE default grayscale score. That isn’t great, but at least it’s a red error instead of green or blue, which would have a more negative effect on image quality. The picture is slightly dull before calibration.
With adjustments in place, the score improves to 1.40dE, which makes the picture more vivid and clear. Visually, all six screens appear identical in this test.
Gamma tracking is solid with a small 0.14 range of values and a 2.27% deviation from the reference. The actual value is 2.25. This is excellent performance.
Color Gamut Accuracy
Our color gamut and volume testing use Portrait Displays’ Calman software. For details on our color gamut testing and volume calculations, click here.
The 27GX790A’s default color results are very good with some hue errors in magenta and yellow, and a slight oversaturation in the red primary. This is easily corrected with a grayscale calibration, which brings all points into their target boxes. Visually, this is the main reason to calibrate. Color is more balanced and vibrant after tweaking.
The sRGB mode is less accurate with oversaturated red, undersaturated green, and hue errors in yellow and cyan. These are small issues, and they can be corrected with calibration if you plan to color grade with your 27GX790A.
Comparisons
The 27GX790A runs a close second in gamut accuracy to the PG27AQDP. Visually, it will be nearly impossible to tell a difference between any of these monitors in terms of accuracy, but when you check out the volume chart, you can see that the top four screens are sporting Quantum Dot tech. That delivers as much as 16% extra color to the red and green sides of the triangle. While the 27GX790A is very colorful, the QD screens are more so.
Test Takeaway: The 27GX790A is slightly disappointing out of the box with a warm-toned image that doesn’t pop as much as some other monitors. Calibration brings it on par with the best screens I’ve tested. It lacks a Quantum Dot layer, so it gives up some color volume to others. But with almost 100% coverage of DCI-P3, it’s plenty colorful.
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