Check the cable connections first

A loose or damaged cable is the most common reason a monitor won't connect. Start by looking at both ends of the cable running from your monitor to your PC — the connector at the monitor end and the connector at the computer end. Push each one in firmly until you hear or feel a click. If the cable has a screw collar (common on older monitors and some professional displays), hand-tighten the screws on both ends.

If the monitor still shows no signal, try a different cable if you have one available. HDMI, DisplayPort, and USB-C cables can wear out or develop internal breaks that aren't visible from the outside. Swap in a cable you know works — even a cable from another device — to rule out a bad connection.

Look at the port itself on both the monitor and PC. If you see bent pins, corrosion, or debris inside the port, that port may be damaged. Try plugging into a different port on your PC if it has more than one video output.

Key Takeaways

  • Push the cable connectors in firmly at both the monitor and PC ends, and hand-tighten any screw collars until they stop.
  • Test with a different cable to rule out a broken connection, since damage inside a cable is invisible from outside.
  • If your PC has multiple video ports (HDMI, DisplayPort, USB-C), try each one because one port can fail while others work.
  • Restart your PC completely, then restart the monitor by unplugging it for 30 seconds, because both devices sometimes need a fresh start to recognize each other.
  • Check your PC's display settings to confirm the monitor is detected and not set to an unsupported resolution or refresh rate.

Restart both devices completely

Before assuming hardware is broken, power down both your monitor and PC fully, then power them back up in the right order. Unplug your monitor from the wall outlet and leave it unplugged for 30 seconds — this clears its internal memory. While the monitor is unplugged, shut down your PC completely (not sleep mode) using the power menu.

After 30 seconds, plug the monitor back in and turn it on. Wait for it to finish starting up (you may see a brief "no signal" message). Then turn on your PC. This sequence gives both devices a clean start and often resolves temporary communication glitches.

Verify the monitor is set to the correct input

Monitors have an input selector that lets you choose which port to display — HDMI 1, HDMI 2, DisplayPort, USB-C, or VGA, depending on your monitor model. If your monitor is plugged into the right port but showing "no signal," it may be set to look at a different input.

Use the buttons on the monitor itself (usually on the bottom or back) to open the on-screen menu. Look for an option called "Input," "Source," or "Signal Select." Cycle through the available inputs until you find the one your cable is actually plugged into. The monitor will show "no signal" for inputs that have nothing connected, so you're looking for the input that either shows your PC's desktop or shows a signal indicator.

Check Windows display settings

If your monitor shows a signal but displays nothing, or if Windows is only showing your desktop on a different screen, the problem may be in your PC's display settings. Right-click on your Windows desktop and select "Display settings" (on Windows 11) or "Display" (on Windows 10).

Scroll down to the "Display" section and look for "Multiple displays." If you see your monitor listed but marked as "Disconnected" or "Not active," click on it and select "Extend" or "Duplicate" depending on whether you want to use just that monitor or add it to an existing setup. Windows sometimes detects a monitor but doesn't automatically turn it on.

Also check the "Advanced display settings" link at the bottom. Make sure the resolution and refresh rate are set to values your monitor supports. If the settings show an unusually high refresh rate (like 240 Hz on a monitor that only supports 60 Hz) or an unsupported resolution, Windows may not be able to display anything. Try lowering both to standard values like 1920 × 1080 at 60 Hz.

Update or reinstall graphics drivers

Your PC's graphics driver is the software that tells Windows how to talk to your monitor. An outdated or corrupted driver can prevent your monitor from being recognized. On Windows, right-click the Start button and open "Device Manager." Look for "Display adapters" and expand that section.

Right-click on your graphics card (it will say something like "NVIDIA GeForce" or "Intel UHD Graphics") and select "Update driver." Choose "Search automatically for updated driver software." Windows will check for a newer version online. If an update is found, install it and restart your PC.

If updating doesn't work, try uninstalling the driver instead. Right-click the graphics card again and select "Uninstall device." Restart your PC. Windows will reinstall a basic driver automatically, which sometimes fixes communication problems with the monitor.

Try a different video port on your PC

Many PCs have more than one video output — for example, both HDMI and DisplayPort, or HDMI and USB-C. If one port isn't working, another one might be. Unplug your monitor cable from the current port and plug it into a different video output on your PC.

If your PC has a dedicated graphics card (common on gaming or workstation PCs), make sure you're using the ports on the graphics card itself, not the ports on the motherboard. The motherboard ports often don't work when a dedicated card is installed. The graphics card ports are usually lower on the back of the PC, clustered together.

Test the monitor on another PC

If you have access to another computer, connect your monitor to it using the same cable. If the monitor works on the other PC, the problem is with your original PC's graphics output or drivers. If the monitor still shows no signal on the second PC, the monitor itself is likely faulty and may need repair or replacement.

This test is especially useful because it narrows down whether the issue is the monitor, the cable, or the PC — three separate components that can each fail independently.

Frequently Asked Questions

My monitor shows "no signal" but the PC is running. What should I try first?

Check that the cable is pushed in firmly at both ends and that the monitor is set to the correct input using its on-screen menu. If both are correct, restart the monitor by unplugging it for 30 seconds, then restart the PC. These two steps fix most "no signal" problems.

I have two monitors and one stopped working. How do I know which port is broken?

Swap the cables between the two monitors. If the problem moves to the other monitor, the port on your PC is broken. If the problem stays with the same monitor, that monitor or its cable is faulty. You can then use the working port for the monitor that still functions.

My monitor works sometimes but keeps losing signal. What causes that?

A loose cable connection is the most common cause. Push the connectors in firmly and check for bent pins. If the problem continues, try a different cable or a different port on your PC. Overheating can also cause intermittent signal loss — make sure your PC has good airflow and isn't blocked by dust.

Can a bad graphics driver prevent my monitor from being detected at all?

Yes. A corrupted driver can stop Windows from recognizing your monitor even if the hardware is fine. Try updating the driver through Device Manager, or uninstall it and let Windows reinstall the basic version. If that doesn't work, the graphics card itself may be failing.

My monitor has multiple input ports but I'm not sure which one my cable is plugged into. How do I find out?

Open the monitor's on-screen menu using the buttons on the monitor body and look at the input or source setting. It will show you which input is currently selected. Then physically trace the cable from your PC to see which port on the monitor it's connected to, and make sure they match.