Helping people with computers... one answer at a time.

No Signal is a message that's not from your computer but from your display device, indicating that it has nothing to display. I'll review possible causes.

I am using Window XP and just started to get a No Signal message when trying to start up. When I push the Panic button on the tower, it starts. Everything works normally after the start. What's going on?

This message actually confuses many people, so you're not alone.

The issue here is that the message is not coming from your computer.

In fact, that's the problem.

Confusing, I know. I'll explain.

PCs and display devices

PC connected to a display device

Your desktop PC is typically connected to an external display device that's variously referred to as the monitor, screen, or display. The video card inside of your PC turns the bits and bytes that represent the image that you see on your screen into a signal that travels along the cable connecting your computer to the display.

And therein lies the clue...

No signal

PC *not* connected to a displayu device

The No Signal message does not come from your computer - it's generated by the monitor itself. All No Signal means is that the monitor is not receiving a video signal from the computer.

That's it.

Possible causes

That's a pretty simple explanation. In fact, from the monitor's point of view, it's a pretty simple situation: it's expecting a signal, telling it what to display, and it's not getting it.

It's easy to overlook some of the possible causes:

  • The monitor is on, but the computer is not.

  • The cable connecting the computer to the monitor has become disconnected.

  • The cable connecting the computer to the monitor is faulty.

  • The monitor has multiple inputs and the wrong one is selected. (This is common if your monitor is actually a TV of some sort.)

  • The computer has multiple screen outputs and the one that the monitor is connected to is not enabled. (This is very common when trying to get an external monitor to work with a laptop.)

  • The computer has crashed in such a way that it's not trying to display anything.

  • The computer is broken in such a way that it cannot boot. (Lights and fans running doesn't mean much in this case.)

  • And, of course, the monitor itself could be broken.

As you can see, there are many possible causes for a simple error message.

When faced with this situation (and I have been!), I check to make sure that everything is on (it's so embarrassing when it's not Smile) and that the cable is properly connected. If that doesn't resolve it, then I move on to trying another cable or monitor and finally attempting to diagnose whether the PC is working at all.

Monitor Messages

Monitors and PC displays have become sophisticated devices in their own right and may often display messages of their own as a result. In the case of no monitor signal, it may be the only thing on the screen.

Other monitor-generated messages will often appear "on top of" whatever else your computer is displaying. There's typically nothing that you can do to your computer to get rid of those messages because they're not from the computer, they're from the monitor. Understanding what they look like and what steps need to be taken means becoming familiar with your monitor's options and controls - something completely separate from the computer itself.

Article C4824 - May 19, 2011 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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9 Comments
Bob S
May 24, 2011 8:44 AM

This happens to me almost every time the computer comes out of standby (Windows XP). I think it means the monitor was off and first turned back on, but the computer is not sending any video just yet -- it's still coming back up from standby. After a few seconds the screen lights up and all is well.

Mike
May 24, 2011 12:11 PM

I guess the question is, what is the "panic button" on the tower, and how would it change the No Signal indication? "Startup" doesn't differentiate between Bootup, or coming out of Hibernate or Standby. However, like Bob S stated, it's most likely a short term indication that will correct itself after several moments for the video card to start sending out display data again.

Keef
May 24, 2011 6:21 PM

"No Signal" can just be a simple problem that as the PC "wakes from sleep" and the video card doesn't wake up fast enough. So the monitor reports no signal. this can sometimes be resolved by just turning the monitor off and on again to flush the message. or by setting the PC bios to "refresh video bios on wake from sleep" STR 3 or some simular bios option found on most modern PCs

Eugen
May 25, 2011 8:48 AM

I had this problem with the "No input signal", but in another way: I had to recover the C partition from a backup, the backup program started, and after 5 minutes a had this message on my monitor. I could not see anymore what is the status of the recovering process... I had a shock, believe me... I found later where the problem was: a setting in W7 to stop the monitor after 5 minutes of inactivity... but until I found that, I really wanted to buy a gun to shot the video card...

NWReader
May 27, 2011 12:24 PM

I had this problem when I had to buy a new monitor. I kept thinking it was because the new monitor was bad and after 3 upgraded monitors later it turned out I really did need a new video card. It's very interesting to see all the different reasons why this might happen. Thanks for all your help, Leo and all responders!

Bernard schwab
May 31, 2011 11:14 AM

Had this problem for weeks.
My video card had an outdated revision.
Updated it and all problems are gone.
Video card:
NVIDIA GeForce FX 5200
Windows XP

Margaret Louk
May 31, 2011 7:43 PM

My monitor has given a no signal notice since I bought it. The monitor came with the package and has a built in speaker. They sounded like an old transistor radio (yes I am that old). So disabled the speakers in the monitor and attached my Bose speakers to the computer and I have great sound. It just keeps giving me the same signal.

Caroline
December 9, 2011 5:37 PM

I use Windows XP Pro on a desktop. A few weeks ago after getting a Blue Screen of Death, I have the same problem and it's driving me crazy! I've checked just about everything I can check, including running several scans of various types and many of the suggestions in this article, including replacing the cable with a brand new one, but the only way I can get my monitor to display anything is to press F8 when booting up and hope I can select "Last known good configuration" before that menu vanishes and the screen goes black again. I have to try several times before the menu stays visible for long enough to do so. Once it's in Windows it's fine, I have no problems at all so if I'm going to be afk for a few hours or so I leave it on rather than go through all that hassle again. Unfortunately, I'm not a hardware expert so I'm reluctant to take the PC apart and I wouldn't know what to look for anyway.

wim
May 18, 2012 7:40 AM

Hello

I get the "no signal" on my screen only after gaming.
I get no display what so ever so I am forced to use the reset button
so my problem is
computer has crashed in such a way that it's not trying to display anything."

Would it be possible to explain this to me, in what way could the pc crash with this problem? It's not trying to display anything, so is it my videocard or something else?

Regards

There's no simple answer. Many different types of crashes could cause video to be turned off.
Leo
18-May-2012

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