ASUS PG27UCDM vs Samsung G81SF: Which 27-inch 4K OLED Fits Your Desk?

The most useful question in this comparison is how many computers will share the monitor. A desktop-only gamer can make a sensible choice around screen finish and checkout price. Add a work laptop, and power delivery and USB switching start to matter every day.

The model names need to match that question. This is the 27-inch Odyssey OLED G8 G81SF, rather than the 32-inch version or the older G80SD. On the ASUS side, the PG27UCDM has features that the similarly named XG27UCDMG does not share. Shopping by the broader “OLED G8” or “27-inch ROG OLED” label obscures the differences you are paying for.

Start with the laptop and peripheral connections

The PG27UCDM accepts video over USB-C DisplayPort Alt Mode and supplies up to 90W of USB-C power. It also has a KVM for sharing USB peripherals. These are the practical advantages highlighted in RTINGS’ direct comparison.

For a desktop and compatible laptop, connect the desktop’s video output and USB upstream connection to the monitor, then use a suitable USB-C connection for the laptop. Attach the keyboard and mouse to the monitor. The KVM switches their USB connection between computers; a desktop’s HDMI or DisplayPort cable alone does not carry that USB connection.

The Samsung has a USB hub, with a USB-B upstream port and two USB-A downstream ports. What it lacks is USB-C video and charging. A laptop therefore needs a separate video path, such as USB-C to DisplayPort, plus its charger. Using the monitor’s USB hub adds the upstream USB connection as well.

Those extra cables are manageable if the laptop stays docked. They become more noticeable when you take it away every morning. An existing dock and USB switch also change the value calculation: replacing equipment that already works buys less convenience than removing a daily cable shuffle.

The ASUS power figure is a ceiling, rather than a promise of 90W charging on every laptop. The computer and cable determine what is negotiated. A power-hungry gaming laptop can still need its original adapter under load. Nor does a USB-C socket turn this monitor into a Thunderbolt dock with the same expansion capabilities.

What both monitors have, and where they diverge

The table combines ASUS specifications and Samsung’s 27-inch product specifications. Screen finishes are also described in the direct testing linked below.

At approximately 166 pixels per inch across the 26.5-inch viewable panel, both offer high pixel density. Moving from one to the other does not increase the number of pixels available for text or games. That is a different upgrade from moving to either monitor from a 1440p screen.

The HDR format entries describe supported paths, rather than a ranking of overall picture quality. Their usefulness depends on the source, software and content. A format badge you never use has little value in a purchase decision built around a particular game library.

Matte versus semi-glossy depends on the room

A light behind your chair can appear in the screen in front of you. Samsung’s matte finish spreads reflections and softens recognizable shapes. The ASUS finish leaves more defined reflections. Neither description alone tells you which will be less distracting at your desk.

In Galaxus’ hands-on comparison, the matte Samsung diffuses reflections over a wider area. That trade-off matters in dark scenes: a distinct reflected object and a broader patch of light are different annoyances. Your window position and ability to move lighting help determine which you prefer.

Coating does not remove the panels’ sensitivity to ambient light. RTINGS notes raised, purple-looking blacks on the Samsung in bright conditions; its ASUS review also identifies raised blacks under ambient light. Buying the matte model therefore does not preserve dark-room black levels in every bright room.

A useful in-person comparison includes a dark game scene and a gray screen, viewed from your normal seating position. Bright showroom footage hides many reflections. This inspection helps choose a surface finish; it is not a substitute for a color measurement.

When DisplayPort 2.1 is worth paying for

The Samsung’s DP 1.4 input supports the advertised 4K 240Hz experience through Display Stream Compression. VESA describes DSC as a low-latency, visually lossless display compression technology. It compresses the transmitted image; it is not an instruction for the game to render fewer pixels.

The ASUS provides a higher-bandwidth alternative. Its UHBR20 connection enables uncompressed 4K 240Hz with a suitable GPU and cable. That is a specific connection capability, rather than an increase in game rendering performance or panel refresh rate.

Your GPU determines whether this advantage is available now. NVIDIA’s comparison lists DP 1.4a for the RTX 4090 and UHBR20 for the RTX 50-series reference specifications. An RTX 4090 cannot acquire UHBR20 output because the display at the other end supports it. For that owner, the ASUS premium needs another justification today, or a deliberate plan to use a different source later.

Likewise, the USB-C input is a separate connection path. The desktop DisplayPort socket’s 80Gbps rating does not establish what a particular laptop can send through USB-C. The laptop’s output, cable and USB configuration determine the available mode. Avoid budgeting for a guaranteed 4K 240Hz laptop setup solely from the monitor’s headline specification.

Console refresh rates and desktop brightness

A 240Hz refresh interval is approximately 4.17ms; at 120Hz it is 8.33ms. These are calculated scan intervals, not measurements of end-to-end input lag. The advertised 0.03ms GTG response refers to pixel transitions. Treating all three as interchangeable “speed” figures obscures what each measures.

For PS5 and PS5 Pro, output tops out at 120Hz. RTINGS’ console testing confirms the ASUS supports 4K up to 120Hz and VRR, while its Samsung review also finds that model well suited to consoles. Whether a game actually produces 120fps depends on the game and mode. The monitor’s unused 240Hz headroom does not change that.

Variable-refresh gaming also brings a shared limitation. RTINGS observed noticeable VRR flicker on the ASUS and distracting flicker on the Samsung with VRR Control disabled as frame rates changed. A higher-bandwidth connection does not establish that either monitor eliminates this behavior.

Desktop brightness is another area where conditions matter. In Galaxus’ SDR comparison, the Samsung reached about 260 nits. The ASUS behaved similarly with Uniform Brightness enabled, but reached up to 471 nits at 10% average picture level with that setting disabled. The latter is not a full-screen white-document brightness figure.

For writing and spreadsheets, a consistent appearance as windows change size has a different value from brighter small areas in a darker scene. Both monitors also retain OLED’s static-content considerations. Charging and KVM features make an office connection more convenient; they do not establish superior resistance to persistent interface elements.

Assign the premium to features you will actually use

Compare checkout totals for the exact regional models, then identify what the more expensive option changes. With these two monitors, another payment does not buy more than 3840×2160 pixels or a refresh ceiling above 240Hz. It buys a preferred finish and, on the ASUS, additional connections and switching.

For a desktop-only setup that suits a matte finish, the Samsung is a strong choice when priced below the ASUS. For a laptop that travels daily between home and work, the ASUS can remove repeated charging and peripheral connections. An UHBR20-equipped PC adds another concrete reason to select it if uncompressed transmission is a purchase requirement.

An existing G81SF owner faces a different calculation: subtract the amount recovered from selling the old monitor from the new purchase total. The remaining cost needs to solve a real dislike of the finish or a recurring connection problem. Switching within the same resolution and refresh class solely for a newer port number leaves much of the experience unchanged.