No Input Signal error message
Tip: This document is for troubleshooting the "no input signal" message when connecting a monitor to a desktop computer. If you are using a laptop, see our steps on connecting a monitor to a laptop.
Note: To connect to a TV, see our page on how to connect a computer to a TV or projector.
Computer not transmitting signal
Make sure the computer has power. If the computer has turned off, it will not be transmitting a signal and cause the "no input signal" message.
Monitor not connected properly
Verify that the monitor is properly connected in the back of the monitor, as well as to the back of the computer. The monitor data cable will connect to the back of your computer using either a VGA connector or DVI connector usually. The pictures below are an example of a VGA cable and the connector on the video card.
If the monitor appears to be connected properly, verify the monitor cable is not loose by disconnecting the cable from the back of the monitor and then reconnect the cable. It's also a good idea to rock the cable back and forth to make sure it's not just loose.
Tip: When disconnecting the cable, make sure none of the cable's pins are bent by examining the end of the cable. If any of the cable's pins are bent or broken, the cable may be defective. It is usually best to replace the cable in this case.
Next, disconnect the monitor cable from the back of the computer and then reconnect the cable. When connecting the cable to the computer, ensure the cable connection is tight. With a VGA style connector, like the one shown above, this cable has screws that can be tightened to hold the connector in place.
Tip: Some computers may have onboard video, as well as an expansion video card. When working with this type of computer, you'll have two different connections for your monitor on the back of your computer. If you see more than one VGA or DVI connector and the monitor is not working, try the other connector.
If the connections appear to be correct, either the monitor or the video card is bad. To test what component is bad, either connect a different monitor to your computer or connect your monitor to a different computer.
- If another monitor works on your computer, the monitor is bad.
- If your monitor works on another computer, your video card is bad. Troubleshoot the bad video card to determine if it is the video card.
Computer not posting
Verify your computer is getting past the POST process and that it is starting up. The "No input signal" message can sometimes appear if the POST process if failing and the computer cannot start up.
If the POST process is failing and the computer is not starting up, it is possible the motherboard could be at fault. A short in the motherboard or a bad capacitor are common causes for a computer motherboard to not pass the POST process.