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Connect the source device’s compatible video output directly to a matching monitor input, select that input on the monitor, and then set the highest resolution and refresh rate that both devices support. A 4K 240Hz monitor can display up to 240Hz, but it cannot make a PC or console output more frames than its graphics hardware and video specification allow. Current ASUS specifications illustrate the distinction: compatible PCs may use 4K at 240Hz on supported inputs, while the listed PlayStation 5 and Xbox Series X use case is 4K at 120Hz with variable refresh rate (VRR), not 240Hz.
The reliable process is therefore a compatibility check followed by a direct connection and a settings check. The exact port, cable capability, Display Stream Compression (DSC) requirement and on-screen-display option depend on the monitor and source model.
What you need to check before connecting
Write down the exact monitor model and the exact PC graphics card or console model. Do not infer capability from the monitor’s headline refresh rate alone. Compare four items:
- Source output: the video outputs on the graphics card, laptop or console and the maximum resolution and refresh-rate modes they support.
- Monitor input: the input type and the modes permitted on that particular port. A monitor may have different limits on DisplayPort, HDMI and USB-C.
- Link requirements: whether the desired mode requires DSC, a particular DisplayPort stream version, or a monitor-menu setting.
- Software mode: the resolution and refresh rate currently selected in Windows, the console system menu and, where relevant, the game.
Use the manufacturer’s manual and specification page for both devices. The ASUS ROG Strix OLED XG27UCDMG, for example, lists DisplayPort 1.4 and HDMI 2.1. The ASUS ROG Swift OLED PG32UCDM lists DisplayPort 1.4 with DSC, HDMI 2.1 and USB-C. Those are examples, not a universal port layout for every 4K 240Hz display.
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Identify the physical ports
On the PC, use a video output on the discrete graphics card rather than a motherboard video connector when the computer has a separate graphics card. On a console, use its HDMI output. On the monitor, note the labels beside each input; the label may include a port number or a capability such as HDMI 2.1.
A USB-C connector does not automatically mean that 4K 240Hz is available. It must carry a video mode supported by both the source and the monitor, and the monitor manual must identify the supported behavior.
Check the cable and any adapter
Use a direct cable and a connection type listed as supported by both devices. An adapter, dock or receiver introduces another link whose limits may be lower than those of the source and monitor. Do not assume that an adapter or a cable marketed for one resolution and refresh rate will provide the same mode on your particular hardware; verify the manufacturer’s specification for the complete path.
How to connect a PC to a 4K 240Hz monitor
- Power off or put the PC and monitor into standby. This is not required for every hot-plug connection, but it makes it easier to identify the intended ports and avoids changing several variables at once.
- Connect the graphics output directly to the matching monitor input. Select the DisplayPort, HDMI or USB-C combination that both manuals list for the desired mode. The ASUS examples use DisplayPort 1.4 and HDMI 2.1; your model may differ.
- Turn on the monitor and PC. If the monitor does not switch automatically, open its on-screen display (OSD) and choose the input number you used.
- Set the Windows display mode. In Windows 11, open Settings > System > Display, select the monitor, then open Advanced display. Choose the highest refresh rate that appears for the selected resolution. If Windows shows 3840 × 2160 at 240Hz, the complete connection is advertising that mode; if it shows only lower rates, continue with the checks below rather than forcing an unsupported setting.
- Confirm the resolution. In Settings > System > Display, select the display resolution identified as 4K (normally 3840 × 2160 for a 16:9 monitor). A high refresh rate at a lower resolution is not the same as 4K at 240Hz.
- Configure the graphics driver only after the Windows mode is available. The GPU control panel may expose additional timing or color options, but selecting a driver option cannot overcome a port, cable, monitor-input or GPU limitation.
- Enable VRR only when the whole setup supports it. Adaptive-Sync, FreeSync or G-SYNC labels vary by monitor and driver. VRR changes how the refresh rate follows the rendered frame rate; it does not turn a 120Hz console output into 240Hz.
When DisplayPort 1.4 and DSC are involved
Some 4K 240Hz monitors use Display Stream Compression (DSC) with DisplayPort 1.4 to carry a high-resolution, high-refresh mode. ASUS identifies DSC on the DisplayPort specification for the ROG Swift OLED PG32UCDM and defines DSC as Display Stream Compression. DSC support must exist on the graphics output and the monitor path; it is not something that can be assumed from the words “DisplayPort 1.4” alone.
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ASUS’s PG32UCDP manual guidance says to choose the DisplayPort stream version according to the graphics card’s supported version. If your monitor has a similar OSD option, select the stream version that the graphics card supports. Changing that option can alter which resolutions and refresh rates are offered, so revisit Windows Advanced display afterward.
How to tell whether the PC is really running 240Hz
- In Windows Advanced display, verify that the active mode line shows both 3840 × 2160 and 240Hz for the intended monitor.
- Check the monitor’s information page in its OSD; many displays show the incoming resolution and refresh rate.
- Look for a stable signal after launching a game. A game can render fewer than 240 frames per second even when the desktop link is operating at 240Hz.
- If the mode disappears after a driver change, return to the monitor input and OSD settings before changing other variables.
How to connect a PS5
- Connect the PS5 HDMI output directly to an HDMI input on the monitor. Use the input that the monitor manual identifies for the supported high-bandwidth mode.
- Select that HDMI input on the monitor. If automatic input detection does not work, use the OSD’s input menu.
- Open the PS5 screen settings. In the console’s display and video settings, set resolution and 120Hz output to automatic or to the highest options the monitor reports as supported. Menu wording can change with system software.
- Check the console’s video-output information page. It should report the negotiated resolution, refresh rate and HDR/VRR availability. Treat that report as the actual link mode, not the monitor’s maximum rating.
The ASUS ROG Strix OLED XG27UCDMG product page describes its console use case as “HDMI 2.1 VRR 4K@120Hz: Ultra-smooth visuals on PS5 and Xbox Series X.” ASUS’s ROG Swift OLED PG32UCDM specifications likewise state 4K/120Hz VRR support for PS5 and Xbox Series X. These statements describe 120Hz console operation on those models; they do not promise 240Hz output from a PS5.
How to connect an Xbox Series X
- Run HDMI from the Xbox Series X to the monitor’s HDMI input. Avoid routing the signal through an unverified switch, receiver or dock while troubleshooting.
- Select the monitor’s HDMI input. Confirm that the monitor reports a signal rather than “no signal.”
- Open the Xbox display settings. In the console’s General > TV & display options area, choose 4K resolution and inspect the refresh-rate choices. Labels can vary by system update.
- Open the 4K TV details screen. Xbox identifies which combinations of resolution, refresh rate, HDR and VRR the connected display reports. Use that screen to distinguish a 4K/120Hz capability from a 240Hz monitor rating.
For the listed ASUS models, the documented Xbox Series X mode is 4K at 120Hz with VRR. The console does not become a 240Hz source because the monitor is rated for 240Hz.
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What about Nintendo Switch 2?
The ASUS ROG Swift OLED PG32UCDM specifications note Nintendo Switch 2 4K output capped at 60 frames per second. That is a separate console limit: a 4K 240Hz display can accept the signal, but the console’s documented output remains 4K/60 in that use case.
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PC and console connection options compared
| Source | Typical direct connection to inspect | What the cited specifications establish | What remains model-dependent |
|---|---|---|---|
| Desktop PC with a compatible graphics card | Graphics-card DisplayPort or HDMI output to the corresponding monitor input | A PC can target 4K/240Hz when the graphics output, monitor input and settings all support it. | GPU model, port capability, cable, DSC requirement, stream-version setting and game frame rate |
| PlayStation 5 | HDMI output to the monitor’s HDMI input | The cited ASUS pages specify 4K/120Hz with VRR for PS5. | Monitor model, selected console mode, VRR behavior and game support |
| Xbox Series X | HDMI output to the monitor’s HDMI input | The cited ASUS pages specify 4K/120Hz with VRR for Xbox Series X. | Monitor model, selected console mode, VRR behavior and game support |
| Nintendo Switch 2 on the cited PG32UCDM example | HDMI output to the monitor’s HDMI input | That specification lists 4K output capped at 60 frames per second. | Whether another monitor or dock exposes different modes |
Why 240Hz may not appear
The wrong input is selected
A monitor can show an image while a different input is selected than the one you intended to configure. Use the OSD input menu, then re-open the source’s display settings. Confirm the monitor’s information page reports the same source.
The source is connected to a lower-capability path
A dock, receiver, KVM, switch or adapter can limit the negotiated mode. Bypass it with a direct source-to-monitor cable. If the direct connection works, compare the intermediary’s published resolution and refresh-rate limits with the desired mode.
The monitor’s OSD stream setting is limiting DisplayPort
If the monitor offers a DisplayPort stream-version selector, follow the manual’s instruction to match the graphics card’s supported version. ASUS specifically documents this type of selection and identifies DSC as Display Stream Compression on its relevant models.
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The graphics output cannot produce the requested mode
A monitor cannot add a missing output mode. If the GPU documentation does not list 4K at 240Hz for the port and connection method in use, select the highest supported combination instead. A lower refresh rate at native 4K is a valid operating mode and may be preferable to an unstable signal.
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Windows or the console is set to a lower mode
Operating systems often retain a previous refresh rate after a display change. Re-select the monitor, open its advanced display or video-output page, and choose the highest mode the system actually lists. Restart the game after changing the desktop or console mode because some games read display capabilities only at launch.
There is a signal, but the game does not reach 240 frames per second
Refresh rate is the display’s scan frequency; frame rate is the number of frames the game renders. A 240Hz desktop link can display a game running at 90, 144 or 200 frames per second. GPU workload, ray tracing, resolution scaling and the game engine determine the rendered frame rate. VRR can reduce tearing when the frame rate varies, but it does not increase the source’s rendering performance.
Safe settings and troubleshooting order
Change one variable at a time so that a successful fix is identifiable. Use this order:
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- Confirm the monitor model, source model and exact ports.
- Remove adapters, docks, receivers and switches for a direct test.
- Select the correct monitor input.
- Check the monitor OSD for DisplayPort stream version, DSC or a bandwidth-related option documented for that model.
- Re-open the source display settings and select the highest mode listed at the desired resolution.
- Power-cycle the monitor and source if the signal remains missing after a mode change.
- Try another port that both manuals list as compatible, then consult the manufacturers’ support documentation if the desired mode is still absent.
Do not repeatedly force an unsupported timing. If an experimental setting produces a blank screen, wait for the source to revert, use another input or cable path to regain a picture, and restore the last known-good mode.
How to choose between 4K/240Hz and 4K/120Hz
For a compatible gaming PC, 4K/240Hz can reduce visible persistence and provide more headroom for high frame rates, but only when the GPU and game can render enough frames and the complete link advertises the mode. For PS5 and Xbox Series X, the documented target on the cited ASUS displays is 4K/120Hz with VRR. A 240Hz monitor is still useful for those consoles because it can operate at their 120Hz mode, but the extra refresh capacity remains unused by the console output.
Choose the mode that is stable at native resolution. A reliable 4K/120Hz signal is better than an intermittent 4K/240Hz signal, and a lower-resolution high-refresh mode may be appropriate only when the game or GPU prioritizes responsiveness over image detail.
Quick Recap
Key takeaways
- Connect the source’s compatible video output directly to the matching monitor input.
- Set resolution and refresh rate in the source after selecting the monitor input.
- Verify the complete path: source output, monitor input, cable, DSC or stream-version setting and software mode.
- Do not treat a 4K 240Hz monitor rating as a promise that every PC or console can output 4K at 240Hz.
- On the cited ASUS examples, PS5 and Xbox Series X are documented at 4K/120Hz with VRR, while a cited Nintendo Switch 2 use case is capped at 4K/60.
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