A 240Hz monitor showing only 120Hz usually means the current display mode or connection path is limited, rather than the panel having lost its capability. Start by confirming the correct screen, its native resolution, and the refresh-rate choices in Windows; then test a direct connection through a supported port.
I would separate two symptoms immediately: Windows offering a maximum of 120Hz, and a game producing only 120 FPS. They can happen together, but they are different problems with different fixes.
First identify what the 120 number represents
A game’s FPS counter reports rendered frames. Windows reports the selected display mode. Some monitor overlays show the incoming signal rate; others show a changing variable-refresh value. None of those numbers should be interpreted without identifying what is being measured.
If Windows is set to 240Hz while your game produces 120 FPS, investigate the game’s frame cap, synchronization, graphics workload, and CPU limits. Changing the cable is unlikely to raise rendering performance simply because the FPS counter shows 120.
If Windows offers only 120Hz, concentrate on mode negotiation and connection capability first. Write down the monitor model, graphics hardware, resolution, and every device between the source and screen. That short inventory prevents you from testing irrelevant fixes or buying a new cable before checking the existing port specifications.
Select the correct monitor and supported resolution
Open Windows Settings, then System, Display, and Advanced display. Select the external gaming monitor if more than one screen is connected. Check the displayed resolution and choose the supported refresh rate for that screen.
A high-refresh option can be available only at particular resolutions. A display marketed with 240Hz capability does not automatically provide that rate at every possible input resolution. Check the manual’s timing table for the exact resolution, port, and mode combination.
I would temporarily use the manufacturer’s native or recommended gaming mode while diagnosing the restriction. If 240Hz appears at one resolution but disappears at another, that is useful evidence about the mode limit. Do not force an unsupported custom timing merely to make the number appear in a menu.
| Symptom | First useful check |
|---|---|
| Windows offers only 120Hz | Supported resolution, input, cable path |
| Windows shows 240Hz; game shows 120 FPS | Game cap and rendering performance |
| 240Hz works directly but not through dock | Dock and source-link mode limits |
| 240Hz appears only at lower resolution | Model-specific timing and bandwidth limits |
Remove docks, switches, and adapters for one test
The display signal travels through a chain. The source port, cable, adapter, dock, switch, and monitor input each have their own capabilities. The weakest relevant part can restrict the final mode, even when every component works at lower refresh rates.
Connect the monitor directly to a suitable graphics output for a controlled test. On a desktop with a dedicated graphics card, confirm that you are using its output rather than assuming the motherboard connector has identical capabilities. On a laptop, consult the specifications for that exact external-display port.
If the missing mode becomes available, the removed equipment is the next item to investigate. Reintroduce one component at a time. This is more informative than swapping several cables and settings together, because you preserve a clear explanation for any improvement.
Check the monitor input and its own settings
Inputs on the same monitor do not always support the same timing combinations. DisplayPort is not automatically necessary for 240Hz, and HDMI is not automatically limited to 120Hz. The exact hardware implementation matters.
Some displays expose higher rates only after an on-screen setting is enabled. Others require a specific input mode or have separate constraints when particular processing features are active. Use the exact model’s manual; do not copy an overclock or compatibility instruction from a vaguely similar model.
If you change a monitor setting, record the previous value and test again. A successful change should make the intended supported mode selectable and stable. Flickering, repeated signal loss, or an unreadable display is a reason to return to the prior working mode and reassess the connection.
Microsoft’s Windows refresh controls explain where to select the display and inspect its available rates.
Test without duplicate displays or extra bandwidth demands
Mirrored screens can lead to mode choices constrained by the combination of displays and their negotiation. As a diagnostic step, test the gaming display on its own or use an extended arrangement rather than duplication. Recheck the choices after the display configuration changes.
At demanding resolutions, color depth and HDR can also change the bandwidth required by a signal. A temporary test with standard color settings may reveal a connection limit. That does not mean HDR is inherently incompatible with 240Hz; the answer depends on the actual resolution, compression support, and link capability.
I would change one variable at a time and restore preferred picture settings after identifying the cause. Randomly reducing resolution, color depth, and refresh together may produce a picture while hiding which component needs replacing.
Update the right software after checking the hardware path
A graphics driver problem can affect display detection and available modes. Install the appropriate driver from the graphics vendor or system manufacturer, restart if required, and recheck the selected display. For laptops, the manufacturer’s recommendations can matter because external ports may be routed through different graphics hardware.
Do not download a “240Hz unlocker” from an unknown website. A utility cannot safely turn an unsupported input path into a supported one. Firmware updates, if the monitor vendor provides them for this exact issue and model, should follow the official instructions.
A full driver-cleaning routine or operating-system reinstall is a poor first move for this symptom. I would reserve disruptive steps for evidence of a software fault after the monitor mode, direct cable path, input capability, and ordinary driver update have been checked.
Distinguish a source-device limit from a monitor fault
A console, laptop, and desktop can offer different display modes through the same monitor input. If one source reaches the documented mode and another does not, that comparison helps narrow the problem without proving either device is defective.
For example, a console output limited to a supported 120Hz mode will not become a 240Hz source because you attach a 240Hz monitor. Likewise, a laptop adapter may expose fewer choices than the laptop’s direct port. Verify each source’s actual capability instead of transferring assumptions from another setup.
I would test the monitor with a known suitable source only if one is already available. Buying another device solely to diagnose the issue is unnecessary in most cases. The official timing tables, a direct connection, and a clear record of the available modes often identify the relevant restriction.
Use a controlled resolution test
Suppose the missing rate becomes available after you reduce resolution. That result suggests that the current signal configuration matters, but it does not identify a defective cable by itself. The source, monitor timing table, intermediate hardware, and link settings still need checking.
Return to the documentation and compare the two exact modes. Record resolution, refresh rate, HDR state, and any relevant color-format setting. Do not leave the display in an unwanted low-resolution mode just because the refresh number is now higher.
I would use the lower-resolution result as evidence rather than a permanent fix. If your monitor is documented to support the desired native-resolution mode through the chosen port, work through the remaining path. If it is not documented, the proper outcome may be choosing the best supported combination rather than forcing a mode the product never promised.
Prepare useful information for support
If ordinary checks do not restore the documented mode, write a short report: full monitor model, source device or graphics card, cable type, direct or adapted connection, operating system, driver version, and the resolutions and rates offered.
Include which tests changed the result. “240Hz appears through a direct DisplayPort connection but not through my dock” is actionable. “I tried everything” hides the one observation that could identify the problem. Describe instability separately from a missing menu option because they can indicate different issues.
I would also say whether the limitation existed from the start or appeared after a specific change. A driver update, new dock, replacement cable, or changed display arrangement provides a useful starting point. Support can then compare your evidence against the documented capability instead of repeating broad troubleshooting from the beginning.
Confirm the fix in Windows and in the game
After 240Hz becomes available, select it and confirm that the screen remains stable. Check the monitor’s signal information where available. Then open the game and inspect its own resolution, display mode, refresh selection, and frame limit.
A game can retain a previous 120Hz setting even after Windows changes. Conversely, a desktop configured at 240Hz does not guarantee 240 FPS in a demanding title. Treat configuration and rendering performance as separate checks.
If the rate remains unavailable through a documented supported direct connection, collect the model numbers, driver version, selected mode, and test results for support. That evidence is more useful than saying the monitor “will not do 240.” Avoid buying replacement hardware until the failing part of the chain has been narrowed down.
Before replacing anything, keep the best working configuration as a fallback. If a test produces a blank screen, let the operating system revert where that option is available and return to a supported mode. The aim is reliable native-resolution operation, not merely getting 240Hz to appear once. A repeatable result after restarting is stronger evidence than a temporary success during several simultaneous changes.
Common questions
Can an HDMI cable run 240Hz?
Yes, when the source, cable, monitor input, and resolution-and-refresh mode support it. Connector type alone is not enough to decide.
Will lowering graphics settings unlock 240Hz in Windows?
Usually it changes game rendering performance rather than the modes reported by the display. Diagnose these separately.
Should I use custom resolutions?
I would first restore a documented supported mode. Custom timings add uncertainty and should not be a substitute for checking the official timing table.