Iiyama Gold Phoenix GB2790QSU Review: Gaming Monitor

With its 240 Hz panel, the iiyama G-Master GB2790QSU-B1 speaks directly to esports enthusiasts and PC competitors: reactivity above all, without neglecting ergonomics. This review is based on the complete published test of the monitor, not on hands-on testing of our own.

The GB2790QSU-B1 carries a 27-inch IPS panel at a Quad HD definition of 2560 x 1440 pixels, refreshed at up to a native 240 Hz, with FreeSync — and by extension G-Sync — compatibility. The maker quotes a 1 ms response time, 400 cd/m² peak brightness, a 1000:1 contrast ratio and 178° viewing angles, and its natural sparring partner in the 27-inch Quad HD 240 Hz class is Samsung's Odyssey G7.

The design is almost too sober for a gaming monitor: well-finished matt black plastics that could pass for plain office equipment, lifted only by a Y-shaped foot slightly more original than the rectangular bases elsewhere in the range. Adjustment is generous where it counts — 13 cm of height travel, tilt from -3° to +18°, and a pivot into portrait mode — though there is no swivel. Remove the foot and VESA 100 x 100 mm mounting is available. The granular matt plastic of the rear is good quality, of a kind previous iiyama models have shown ages well, and every connector faces downward towards a small lug at the base of the arm that serves as basic cable management.

Connectivity covers one HDMI input, one DisplayPort input, a headphone output and two USB 3.0 ports — none of them, regrettably, on the edge of the screen for easy reach. Two 2 W speakers are far from exceptional but serve for system sounds and short videos. The on-screen display is driven by five buttons on the underside of the screen; they are impractical and invite frequent mis-presses, where a joystick — as fitted to some of the brand's other models — would have served better.

On a desk, the foot's 25.6 cm depth is not especially compact, though its airy shape leaves room for keyboard and mouse. The Quad HD definition works out at a modest 109 pixels per inch on this diagonal: excellent for games, all the more so at 240 Hz, and comfortable enough for desktop work and browsing, with a usefully large workspace for a 27-inch screen.

Straight from the box the calibration is rather good. The measured average delta E of 2.8 sits below the threshold of 3 beyond which the human eye perceives colour deviations — red, blue and cyan flirt with a delta E of 5, but the overall rendering is very satisfying. Colour temperature averages 6280 K, close to the 6500 K reference, on a perfectly stable curve across the spectrum. Only the gamma curve wobbles slightly, averaging 2.3 against the 2.2 reference, with dark greys very slightly under-exposed relative to light ones; reducing brightness to obtain a white near 150 cd/m² changes nothing. Probe calibration steadies the temperature and gamma curves and brings the average delta E down to 1.8, though blue stays above 3.

The measured native contrast of 1140:1 is very good for an IPS panel yet a touch behind rivals of the class, and far from the best VA monitors, whose ratios exceed 4000:1. In practice that means washed-out blacks in a dark room; in daylight, or a normally lit room, it hardly registers at all.

The GB2790QSU-B1 does not use pulse-width modulation to govern its brightness, so it is free of flicker and the headaches it can cause sensitive users, and a software blue-light reduction mode sits in the OSD. Adaptive sync operates between 40 and 240 Hz, which does demand a powerful graphics card to exploit fully — driving 240 fps at native Quad HD suggests a GeForce RTX 3070 Ti or Radeon RX 6800 XT as a sensible minimum — and in operation the image stays fluid, free of tearing and micro-stutter.

The headline number is the measured persistence of just 4.5 ms with overdrive set to 4 (the maximum setting of 5 introduces a touch of reverse ghosting). That places this iiyama among the most reactive monitors of its generation: level with the 240 Hz VA panels of Samsung's Odyssey G7 and G9 while offering the wider viewing angles of IPS, and level with a 280 Hz Full HD IPS rival; in the published measurements only a TN panel did better, at 3 ms, with all the viewing-angle and contrast compromises TN brings — and OLED, only just arriving, will be unbeatable on this metric. Display lag measured at 11.6 ms (at 60 Hz) translates to an almost imperceptible delay between a mouse or keyboard action and its effect on screen.

Set to a white of around 150 cd/m², the monitor draws about 20.9 W — a relative consumption of 101 W/m², in line with the tested average of 100 W/m². At minimum brightness (113 cd/m²) it uses 19 W; at maximum (530 cd/m², measured at 240 Hz) 43 W. Moving from 60 to 240 Hz adds roughly 4 W.

Low persistence and reduced display lag make the G-Master GB2790QSU a very good gaming monitor and an excellent choice for competitors — but not only for them. It is also well calibrated from the factory and offers enough adjustment for comfortable everyday use.