Iiyama G-Master GB2870UHSU Review: 28-Inch IPS Monitor

The iiyama G-Master GB2870UHSU stands among the more affordable Ultra HD monitors capable of 120 Hz, with an HDMI 2.1 input handling 4K 120 Hz and VRR — exactly what the latest generation of games consoles ordered. This review is based on the complete published test of the monitor, not on hands-on testing of our own.

The GB2870UHSU carries a 28-inch IPS panel at an Ultra HD definition of 3840 x 2160 pixels, and separates itself from the crowd with a native 150 Hz refresh rate and that HDMI 2.1 input supporting 4K 120 Hz and Variable Refresh Rate — perfectly suited to an Xbox Series S/X or PlayStation 5. Fairly complete ergonomics and a USB 3.0 hub round out the case. Monitors of this 4K/120 class remain expensive as a breed; this one sits towards the accessible end of it alongside rivals from ViewSonic and Samsung's Odyssey range.

In the line of the maker's other models, the design is very classical: well-finished matt black plastics, no RGB lighting, no gaming affectation — it could pass for an office monitor. The airy Y-shaped foot leaves plenty of desk space free, and a basic cable-management channel at the rear gathers three or four cables at most. Height adjusts across 13 cm, tilt spans -3° to +18°, and a pivot allows portrait orientation; there is no swivel. The rear is the same sober granular matt black plastic that ages well on iiyama models, and VESA 100 x 100 mm mounting is available with the foot removed.

Connectivity comprises the HDMI 2.1 input (4K 120 Hz, VRR), a DisplayPort input, a headphone output and three USB 3.0 ports — none, once again, on the screen's edge. Two 2 W speakers serve for short videos rather than serious listening. The on-screen display is driven by five touch-sensitive keys on the front — less practical than the clickable joystick iiyama fits to some models — but the interface is clear and the settings numerous.

The foot's 25.6 cm depth is not especially compact, though its openness leaves room for keyboard and mouse. Ultra HD on a 28-inch diagonal works out at 157 pixels per inch — all but unusable without scaling, but current Windows and macOS releases handle 150% or 200% scaling cleanly, leaving text legible and the image perfectly sharp. Photo-editing software exploits the native definition to display images at an exceptional level of detail, a genuine draw for retouching enthusiasts. In games, the benefit of Ultra HD on this diagonal is less clear-cut against Quad HD — particularly if 150 frames per second is the target — but for console players the 4K 120 Hz support is a real advantage.

Default calibration is rather good: an average delta E of 2.4 sits below the perceptibility threshold of 3, with only red exceeding a delta E of 5. Colour temperature averages 6200 K, close to the 6500 K reference, on a perfectly stable curve. The gamma averages 2.3 — near the 2.2 reference — but its curve lacks stability at the dark end of the spectrum, leaving dark greys slightly crushed, and no setting corrects it; reducing brightness to reach a white of about 150 cd/m² changes little. Probe calibration is the one route to stabilising the temperature and gamma curves, bringing the average delta E down to 1.1 with no shade above 3.

Native contrast measured 1130:1 — very good for IPS, slightly behind the best of the class and far from VA monitors exceeding 4000:1. In practice that means washed-out blacks in a dark room and little to notice in daylight. The HDR compatibility is of limited interest: the peak brightness is simply too low to deliver it.

Brightness is regulated without pulse-width modulation, so the panel is flicker-free, and a software blue-light mode sits in the OSD. FreeSync operates across a wide 48-150 Hz window covering every use. Feeding the native Ultra HD definition at high frame rates demands a very powerful graphics card — a Radeon RX 6800 XT or GeForce RTX 3090 class board — and in operation the image stays fluid, free of tearing and micro-stutter.

Measured persistence is 5 ms with overdrive at level 4 (the maximum setting introduces slight reverse ghosting), placing the GB2870UHSU among the most reactive monitors around — just behind the 4.5 ms recorded by the 240 Hz class, including its own stablemate the G-Master GB2790QSU. Display lag is a non-issue in practice.

At a white of around 150 cd/m² the monitor draws about 25 W — a relative 116 W/m², slightly above the 100 W/m² average of tested monitors. Minimum brightness (41 cd/m²) uses 19 W; maximum (310 cd/m²) 37 W, measured at 60 Hz, with the step from 60 to 150 Hz adding roughly 4 W.

The G-Master GB2870UHSU is a very good Ultra HD monitor that pairs a well-calibrated image with a 150 Hz refresh rate, and its HDMI 2.1 connectivity makes it perfectly at home with the 4K 120 Hz and VRR of a PS5 or Xbox Series console. It will delight console players who also want to enjoy their PC. Its middling contrast, elevated consumption and token HDR capability are what keep it short of a fifth star.