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Connect the source directly to a compatible monitor input, select that input, and then set the resolution and refresh rate in the source device. A 240Hz label on the monitor does not make a PC or console output 240Hz: the graphics hardware, port mode, cable and monitor input must all support the selected signal.
On a compatible PC, 4K at 240Hz may require DisplayPort 1.4 with Display Stream Compression (DSC) or HDMI 2.1, depending on the exact monitor and graphics card. PlayStation 5 and Xbox Series X setups documented by ASUS use 4K at 120Hz with variable refresh rate (VRR), not 240Hz.
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What you need to establish before plugging anything in
A successful connection has four separate parts: the source output, the cable and link mode, the monitor input, and the operating-system or console setting. The weakest part determines the available modes. A monitor can refresh at 240Hz internally while showing a lower refresh rate because the connected device cannot transmit 4K at 240Hz.
1. Identify the exact monitor inputs
Read the specification page or manual for the precise model, not just the product family. Look for the input type and the maximum resolution and refresh rate supported by that input. Ports on the same monitor can have different capabilities, and a monitor may reserve its highest mode for one input or for a particular compression setting.
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For example, ASUS lists the ROG Strix OLED XG27UCDMG with DisplayPort 1.4 and HDMI 2.1. ASUS also lists the ROG Swift OLED PG32UCDM with DisplayPort 1.4 with DSC, HDMI 2.1 and USB-C. Those are model-specific examples; they do not establish that every 4K 240Hz monitor has the same ports or limits.
2. Identify the source outputs
Check the graphics card’s physical outputs and its documentation for supported 4K refresh-rate modes. On a desktop PC, use an output on the discrete graphics card rather than an unused video connector on the motherboard when the monitor is intended to run from the discrete GPU. A laptop may route its external connector through integrated graphics, so its manufacturer specification matters.
For a console, check the console’s supported output modes and use its HDMI output. The monitor’s 240Hz capability does not change the console’s own frame-rate ceiling.
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Connect the source directly to the matching monitor input whenever possible. Use the cable supplied with the source or monitor when it is suitable for the desired mode, or a cable whose capabilities are documented for both devices. Do not assume that an adapter, dock or older cable will preserve every resolution, refresh rate or VRR feature. Compatibility depends on the exact devices and the selected mode.
4. Check whether DSC or a monitor setting is involved
DSC means Display Stream Compression. ASUS identifies DSC with DisplayPort on the cited 4K 240Hz specifications. Some monitors expose a DisplayPort stream-version or DSC option in the on-screen display (OSD). The ASUS manual excerpt for the PG32UCDP says to choose the DisplayPort stream version according to the graphics card’s supported version. If the monitor manual calls for a particular stream version or DSC state, follow that model-specific instruction.
PC connection: a complete setup procedure
Step 1: Shut down or put the PC in standby
Powering down is not always required for a modern hot-plug connection, but it removes uncertainty while you identify ports and prevents you from changing several variables at once. Turn the monitor off as well if you are replacing an existing cable.
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Step 2: Connect the graphics output to the matching monitor input
- Locate the DisplayPort or HDMI output on the graphics card. Do not connect to a different port merely because it fits.
- Connect the cable to the corresponding input on the monitor. If the monitor has multiple HDMI or DisplayPort sockets, note which one you used.
- Remove any intermediate switch, receiver, dock or adapter during initial setup. Add those devices only after the direct connection works at the required mode.
- Reconnect power and turn on the monitor before starting the PC, if the monitor manual recommends that order.
Step 3: Select the monitor input
Many monitors detect an active source automatically. If the screen remains blank or shows the wrong device, open the monitor OSD, choose Input or Source, and select the exact DisplayPort or HDMI socket in use. Menu names vary by model, so use the manual’s label rather than guessing.
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Step 4: Set the Windows display mode
- In Windows, open Settings > System > Display.
- Select the connected monitor if more than one display is shown.
- Open Advanced display.
- Choose the monitor’s refresh-rate selector and select the highest 4K mode that the complete setup offers. Confirm that the resolution remains 3840 × 2160 (4K UHD) rather than dropping to a lower resolution.
Windows only lists modes negotiated successfully between the GPU, cable, input and monitor. If 240Hz is absent, do not force a random custom mode before checking those four elements.
Step 5: Configure the graphics driver when necessary
Open the control panel supplied with the graphics driver and confirm that the same monitor is selected, the output is set to 4K, and the color and timing options are not reducing the available mode. Driver panels use different labels and change over time; the monitor’s documented input limits and the GPU’s documentation take precedence over a generic preset.
Step 6: Enable VRR only after the basic mode works
If the monitor and graphics hardware support a variable-refresh feature, enable it in the monitor OSD and in the graphics settings after establishing a stable 4K refresh rate. VRR is separate from the monitor’s maximum refresh number: it allows the display to follow changing frame rates within its supported range, but it cannot create frames that the GPU does not render.
Step 7: Verify outside a game
Use Windows Advanced display to confirm the active resolution and refresh rate. Then check a game or application that offers its own display settings. A game can select a different resolution, run in a compatibility mode or cap its frame rate even when Windows is correctly set to 240Hz.
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Console connection: PlayStation 5
What the cited monitor specifications support
ASUS’s product pages for the cited 4K 240Hz monitors describe PlayStation 5 use at 4K/120Hz with VRR. ASUS’s wording for the ROG Strix OLED XG27UCDMG is: “HDMI 2.1 VRR 4K@120Hz: Ultra-smooth visuals on PS5 and Xbox Series X.” This is a model-specific console mode, not a promise of 240Hz output from a PS5.
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Connection steps
- Connect the PS5 HDMI output directly to the monitor’s HDMI 2.1 input identified in the monitor documentation.
- On the monitor, select that HDMI input.
- On the PS5, open Settings > Screen and Video > Video Output. Menu wording can change with system software.
- Set resolution to 4K or Automatic, enable 120Hz Output when available, and enable VRR when the monitor and current game support it.
- Review the PS5 information screen to see the detected resolution, 120Hz capability and VRR status.
If the PS5 reports 4K at 60Hz only, recheck that the cable is connected to the intended HDMI input, that the monitor’s HDMI mode is not set to an older compatibility option, and that the monitor specification explicitly supports 4K/120Hz on that input.
Console connection: Xbox Series X
What to expect
The ASUS specifications reviewed describe Xbox Series X at 4K/120Hz with VRR on the listed monitors. The console therefore uses the monitor’s high-refresh capability, but not the full 240Hz rating.
Connection steps
- Connect the Xbox Series X HDMI output directly to the monitor’s documented HDMI 2.1 input.
- Select that HDMI input in the monitor OSD.
- On the Xbox, open Settings > General > TV & display options.
- Set the resolution to 4K UHD and refresh rate to 120Hz when those options are available.
- Open 4K TV details to see which 4K, 120Hz and VRR capabilities the console has detected.
If a capability is marked unavailable, first test the direct cable connection and the monitor’s documented HDMI mode. A 240Hz monitor cannot make the Xbox report a 240Hz output option that the console does not provide.
PC versus console: what each connection can deliver
| Source | Connection to test first | Mode documented in the cited examples | Important qualification |
|---|---|---|---|
| Compatible PC graphics card | DisplayPort 1.4 or HDMI 2.1, matching the monitor and GPU | 4K at 240Hz may be available when the GPU, input and settings support it; ASUS identifies DSC with DisplayPort on a cited model | Check the exact graphics-card and monitor specifications. The monitor’s rating alone is not sufficient. |
| PlayStation 5 | HDMI from the console to the monitor’s compatible HDMI input | 4K at 120Hz with VRR on the cited ASUS models | Do not promise 240Hz output from the PS5. |
| Xbox Series X | HDMI from the console to the monitor’s compatible HDMI input | 4K at 120Hz with VRR on the cited ASUS models | Do not promise 240Hz output from the Xbox Series X. |
| Nintendo Switch 2 (on the cited PG32UCDM specification) | HDMI, subject to the console and monitor documentation | 4K output capped at 60fps on that specification | This is a note for that cited monitor page, not a universal statement about every monitor or every Switch 2 configuration. |
How to get 240Hz at 4K on a PC
Getting the option to appear is a compatibility check, not a monitor-menu trick. Work through the chain in this order:
- Confirm the GPU mode. The graphics card must document 3840 × 2160 at 240Hz on the output you plan to use. If it does not, the monitor cannot supply that mode.
- Confirm the monitor input mode. Check whether 4K/240Hz is assigned to DisplayPort, HDMI, or both. Confirm whether DSC is required for the DisplayPort mode.
- Use the appropriate port on both ends. A cable that fits physically can still connect two ports whose negotiated mode is lower.
- Set the monitor’s stream option if present. If the OSD offers DisplayPort stream version or DSC, use the setting recommended for the GPU. The cited ASUS manual guidance is to select the stream version according to graphics-card support.
- Select 4K and 240Hz in Windows. Choose the highest listed mode under Advanced display and verify the resolution did not change.
- Check the application frame rate. A desktop refresh setting of 240Hz does not mean every game renders 240 frames per second. Game limits, graphics quality and the GPU’s workload determine rendered frame rate.
If 240Hz appears at a lower resolution but not at 4K, the link is negotiating a mode limit; revisit the GPU specification, monitor input specification, DSC requirement and cable path rather than assuming the monitor is defective.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Ports, DSC and input selection explained
DisplayPort 1.4
DisplayPort 1.4 is the interface identified on both cited ASUS examples. On the PG32UCDM specification, ASUS explicitly pairs DisplayPort 1.4 with DSC. Whether a particular GPU can use the monitor’s 4K/240Hz DisplayPort mode depends on that GPU’s output implementation and the monitor’s accepted stream settings.
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HDMI 2.1
HDMI 2.1 is the interface identified on the cited ASUS monitors for the console use case. The presence of an HDMI 2.1 socket does not by itself guarantee that every connected source will output 4K at 240Hz; the source and the monitor’s port mode must both support that combination. For the cited PS5 and Xbox Series X setups, the documented target is 4K/120Hz VRR.
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The PG32UCDM specification includes USB-C in addition to DisplayPort 1.4 with DSC and HDMI 2.1. Treat USB-C as a separate model-specific input: verify the monitor manual and the computer’s USB-C video-output capability before relying on it for a high-refresh 4K signal.
Troubleshooting when the screen is blank or the mode is missing
No image at all
- Confirm the monitor is powered and its input selector matches the socket used.
- Reseat both ends of the cable and test a direct connection without a dock, switch or adapter.
- Try another documented input only if the source and monitor support the same mode on that input.
- On a desktop, verify that the cable is connected to the graphics card output you intend to use.
Image works, but only at 60Hz
- Open the source’s display settings and explicitly choose the monitor’s high-refresh mode.
- Check whether the monitor input is in a compatibility mode or whether its OSD stream setting is mismatched with the GPU.
- Confirm the cable and every intermediate device are suitable for the selected mode.
- For PS5 or Xbox Series X, confirm the console is set to 4K and 120Hz and inspect its video-information page. The documented console ceiling for the cited ASUS examples is 120Hz.
240Hz is listed, but only at a lower resolution
This usually means the source and link can negotiate a high refresh rate but not the combination of 4K and 240Hz. Recheck the GPU’s published output modes, the monitor input’s 4K/240Hz specification and any DSC requirement. Do not treat a custom resolution as proof that the complete signal is supported.
VRR is unavailable
- Enable VRR in the monitor OSD and in the source settings after establishing the basic resolution and refresh rate.
- Use the input documented for VRR; ports on the same monitor may not have identical feature sets.
- Check that the console or graphics driver recognizes the display as VRR-capable.
- Remember that VRR follows the source’s changing frame rate; it does not increase the source’s maximum frame rate.
The signal drops out or flickers at 240Hz
Return temporarily to a lower refresh rate, remove adapters and switches, and test the direct connection again. Then verify the monitor’s recommended stream version or DSC setting and the graphics card’s supported output. If the lower mode is stable but the advertised mode is not available through the exact connection, the limitation may be the source, cable path or input specification rather than the panel.
How to verify the final result
Verification should happen at three levels:
- Monitor OSD: many monitors show the incoming resolution and refresh rate in an Information panel. Use the model manual to find it.
- Operating system or console: Windows Advanced display, PlayStation video-output information and Xbox 4K TV details show what the source believes it is sending.
- Application: a game’s own display page may apply a frame-rate cap or exclusive mode. Confirm its resolution and cap separately from the desktop setting.
Record the working input, cable route and settings. That makes it easier to restore the correct mode after a driver update, console reset or monitor firmware change.
Practical decision guide
Choose a PC connection when you want the monitor’s full 240Hz capability
A PC is the only source in the cited material for which 4K/240Hz is presented as a possible target. It still requires a graphics card and monitor input that support the mode, plus any required DSC or OSD configuration. Check the exact pair of specifications before buying or changing hardware.
Choose the console’s HDMI connection when 4K/120Hz VRR is the goal
For PS5 and Xbox Series X, use the monitor’s documented HDMI input and configure 4K/120Hz with VRR where supported. Buying a 240Hz monitor can provide headroom for a future or different source, but the cited console configurations remain 120Hz.
Do not buy an adapter as a first fix
An adapter may be appropriate for a specific, documented compatibility problem, but no adapter or cable is universally required for every 4K 240Hz setup. Establish the direct source-to-monitor connection and identify the exact unsupported link before adding hardware.
Quick Recap
Key takeaways
- Match the source output to a monitor input that supports the desired mode; then select that input.
- Set resolution and refresh rate in Windows or the console’s video settings and verify the negotiated result.
- ASUS’s cited 4K 240Hz examples use DisplayPort 1.4 and HDMI 2.1; one specification explicitly identifies DisplayPort DSC, while another also lists USB-C.
- The cited PS5 and Xbox Series X use case is 4K/120Hz VRR, not 240Hz.
- When a mode is missing, check the source capability, monitor input, cable path and DSC or stream-version setting in that order.
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