LG UltraGear OLED 27GX790B review: 540Hz speed with a 720Hz trick

LG's UltraGear OLED line has become a go-to choice for 27-inch gaming monitors. The newest flagship in that size is the UltraGear OLED 27GX790B, which first appeared in China in December 2025 and is now sold in other regions, including the US. It follows the 480Hz 27GX790A and pushes refresh rates even higher, to 540Hz at 1440p or 720Hz in a lower-resolution mode.

This LG UltraGear OLED 27 review is based on LG's specifications, detailed coverage from monitor specialist TFTCentral and owner reports. The takeaway: this is a monitor for serious competitive players, and it also looks excellent for everyday gaming, as long as your PC can keep up.

Design and ergonomics

The 27GX790B has a virtually borderless flat screen on a stand that adjusts for tilt, height, swivel and rotation into portrait mode. The back has hexagonal RGB lighting that you can customise or switch off.

LG includes gaming extras such as Black Stabilizer, on-screen crosshairs and an FPS counter, plus picture-in-picture and picture-by-picture for two sources. The LG Switch feature lets you save picture presets for work, gaming and streaming and apply them with a hotkey.

Panel technology and picture quality

The monitor uses LG Display's 4th-generation WOLED panel with a four-layer Primary RGB Tandem structure. In practice, that means stronger colour and higher brightness than earlier WOLED panels. Coverage is about 99.5% of the DCI-P3 colour space, and contrast is effectively infinite, with per-pixel dimming giving perfect blacks in dark rooms.

The panel is 1440p on a 27-inch screen (26.5-inch viewable), or about 110 pixels per inch. That is sharp for gaming, though WOLED panels without an RGB-stripe subpixel layout can show slight colour fringing around small text, which some people notice in office work.

LG uses a matte anti-glare coating, as opposed to the glossy finish on some rival 540Hz monitors. Matte is better at controlling reflections from windows and lamps, but in a bright room it can make blacks look slightly greyer than on glossy screens.

Brightness and HDR

The 27GX790B carries VESA DisplayHDR True Black 500 certification. The specifications list up to 1,500 nits for very small highlights (1.5% of the screen), 800 nits at a 10% window and 335 nits for a fully white screen. Small HDR highlights such as explosions and sunlight can therefore be very bright, while large bright scenes are limited, as on all OLED monitors.

Earlier in 2026, TFTCentral investigated reports of 'grey banding' artefacts on some tandem WOLED panels, which can appear on dark grey tones in certain situations. It is worth checking your unit when it arrives and knowing your retailer's return policy.

Gaming performance: 540Hz and 720Hz

Motion clarity is the core selling point. The 0.02ms response time and 540Hz refresh rate make fast motion extremely clear, and the monitor is certified for VESA ClearMR 21000. Variable refresh rate works with NVIDIA and AMD graphics cards through G-Sync Compatible and FreeSync Premium Pro support.

Dual mode switches the display to 1280 x 720 at 720Hz, which TFTCentral noted was the highest refresh rate available on an OLED monitor when it launched. It is aimed at esports players in games like shooters where frame rates can climb very high. Note that LG does not list a black frame insertion mode.

To benefit, you need a powerful graphics card and games that can run at hundreds of frames per second. For single-player titles at high settings, most PCs will not come close to 540fps, so a cheaper 240Hz or 360Hz OLED may deliver a similar experience.

Connectivity and burn-in care

Inputs include two HDMI 2.1 ports and one DisplayPort 2.1 port. The DisplayPort input uses UHBR13.5, which is not enough bandwidth for the full 540Hz signal without Display Stream Compression, although DSC is widely supported by modern graphics cards. A USB-C port with DisplayPort Alt Mode suits laptops, and there are two USB-A ports and a headset jack.

OLED panels can suffer burn-in from static images over time. LG includes OLED Care features to reduce that risk, and TFTCentral reported a three-year warranty at launch. Check the warranty terms in your country, and use dark themes, hide taskbars and let the monitor run its refresh cycles.

LG 27GX790B vs 27GX790A

The older 27GX790A offers 1440p at 480Hz and remains an excellent monitor, often at a lower price. The 27GX790B adds a faster 540Hz native refresh, the 720Hz dual mode and a newer tandem panel for higher peak brightness. If you do not play competitive games at extreme frame rates, the 27GX790A or another 240Hz OLED may be better value.

Key specs

Panel

26.5-inch 4th-gen WOLED, Primary RGB Tandem, flat, matte anti-glare

Resolution / refresh

2560 x 1440 at 540Hz; dual mode 1280 x 720 at 720Hz

Response time

0.02ms (GtG)

Brightness

335 nits full-screen SDR; 800 nits at 10% window; up to 1,500 nits at 1.5% window

HDR / colour

VESA DisplayHDR True Black 500; about 99.5% DCI-P3

Adaptive sync

NVIDIA G-Sync Compatible, AMD FreeSync Premium Pro

Ports

2x HDMI 2.1, 1x DisplayPort 2.1 (UHBR13.5), USB-C with DP Alt Mode, 2x USB-A, headset jack

Stand

Tilt, height, swivel and pivot; hexagonal rear lighting

Alternatives to consider

• LG UltraGear OLED 27GX790A: The previous 480Hz model, a strong choice if you want to spend less.
• ViewSonic XG273F-2K-OLED: Another 27-inch 540Hz WOLED with a 720Hz dual mode, reportedly with a glossy finish.
• ASUS ROG Strix OLED XG27AQDMG: A 27-inch 1440p WOLED with a glossy coating for deeper-looking blacks at a lower refresh rate.

Frequently asked questions

The LG UltraGear OLED 27GX790B is a showcase for what OLED gaming monitors can do in 2026: extremely fast, bright in highlights and practical in lit rooms thanks to its matte coating. It is overkill for many players, and the price reflects that, but for competitive gamers with the hardware to match, it is one of the best 27-inch monitors you can buy.

How we research: Reviews are based on the maker’s specifications, published independent tests and owner reports. Scores compare the product with others in its class.