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Fix a monitor that has no signal

We'll rule out cable, input selection, and source output, then isolate the cause—cable fault, GPU, or port—or tell you when to call a pro.

Troubleshooting · Home maintenance
5–15 min
What you'll need
  • Known-good video cable (HDMI, DisplayPort, or VGA)
Step 1 of 7

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Steps

Goal: Confirm the symptom, rule out cable and input, then isolate the cause.

Check cable and input

Goal: Rule out loose connection and wrong input selection.

  • Reseat the video cable at both the monitor and the PC. Check for bent pins on VGA or DVI.
  • Use the monitor input or source button to select the correct port (HDMI 1, HDMI 2, DisplayPort, etc.).
  • Confirm the PC is on and not in sleep. For laptops, press the function key to enable external display (e.g. Fn+F4).
  • Good: Cable secure and input correct. Proceed to Rule out the source.
  • Bad: Still no signal—try a different cable and port.

Rule out the source

Goal: Determine whether the monitor or the PC is the problem.

  • Try a known-good video cable. Try another port on the PC and monitor.
  • Power off both devices. Unplug the monitor for 10 seconds. Power on the monitor first, then the PC.
  • Update graphics drivers from the manufacturer site if the monitor worked before.
  • Good: Signal restored. If not, try another PC to isolate monitor vs GPU.
  • Bad: No signal with multiple cables and sources—call a technician.

When to get help

Call a technician if:

  • The monitor shows no signal with multiple cables and sources.
  • The PC does not output to any monitor (GPU may have failed).

Verification

  • The monitor displays the desktop or video from the connected source.
  • No “No signal” or “Check cable” message.
  • Correct resolution and refresh rate.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify the monitor shows a no-signal message (not just black).
  2. Cable and input Reseat cable, select correct input on monitor.
  3. Try different cable and port Swap cable and try another port on PC and monitor.
  4. Restart and drivers Cold restart both devices; update graphics drivers.
  5. Call a pro No signal with multiple cables and sources—GPU or input board may have failed.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Cable type and connections
  • Input selected on monitor
  • PC model and GPU
  • Steps already tried

Does the monitor show "No signal" or "Check cable" on screen?

If the monitor displays a message, it has power and is waiting for a signal. If completely black, see fix-monitor-will-not-turn-on.

Check the on-screen message. No signal / Check cable: cable or source issue—proceed. Completely black: power issue—see fix-monitor-will-not-turn-on.

Yes No (black screen)

You can change your answer later.

Is the cable firmly connected and the correct input selected?

Loose cable or wrong input are the most common causes.

Reseat the cable at both ends. Use the monitor input button to select the correct port (HDMI 1, DisplayPort, etc.). Good: cable secure, input correct—check source. Bad: still no signal—try different cable and port.

Yes No

You can change your answer later.

Is the PC on and outputting to the display?

PC must be on and configured to output to the external monitor.

Wake the PC. For laptops, press Fn+F4 (or similar) to enable external display. Check that the PC is not in sleep. Good: PC outputting—restart both devices. Bad: PC not outputting—check GPU and drivers.

Yes No

You can change your answer later.

Try a different cable and port

Swap the cable for a known-good one. Try another port on the PC and monitor. If still no signal, restart both devices and update graphics drivers.

Done

Restart both devices and retest

Power off PC and monitor. Unplug monitor 10 seconds. Power on monitor first, then PC. If still no signal, update graphics drivers.

Done

Update graphics drivers

Download the latest driver from NVIDIA, AMD, or Intel. Install and restart. If the monitor still shows no signal with multiple cables and sources, the GPU or input board may have failed—call a technician.

Done

Call a technician

Call a technician if the monitor shows no signal with multiple cables and sources, or if the PC does not output to any monitor. GPU or monitor input board may need replacement.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a monitor show no signal?
Loose or faulty cable, wrong input selected on the monitor, PC or source not outputting, or a failed GPU or port. Check cable and input first—most issues are connection-related.
Can I fix a monitor that has no signal myself?
Yes. Reseat the cable, select the correct input, and confirm the PC is on and outputting. Try a different cable or port. If the monitor works with another device, the original source may be the issue.
When should I call a technician for no signal?
If you have tried multiple cables and ports and the monitor works with another PC but not yours—the GPU may have failed. If the monitor shows no signal with any source, the input board may have failed.

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