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

Windows has stopped sending a signal to your monitor. It's probably crashing randomly. I explore what that means.

Leo, I have an intermittent problem. Sometimes when I boot up, my screen will show the Windows 7 flag for a bit and then all of the sudden, I get the "No signal" message on my monitor and the video is gone. As I said, it is intermittent. It may happen once every few days or may go as long as three weeks and then it rears its ugly head. Any ideas you can give me would be appreciated. Thank you.

In this excerpt from Answercast #36, I look at a system that is hanging and not sending a signal to the monitor. Time for some troubleshooting.

No signal

All that really means is that Windows on your computer has stopped sending a signal to your monitor.

  • What that normally means is that Windows has crashed – plain and simple.

It just means that the system (in your case, during the boot process) has, for some reason, failed to boot and crashed completely. The machine has become hung in such a way that the video card is no longer attempting to send anything to the monitor.

Intermittent signal

Now, as to why that might be happening? Gosh, you got me!

It could be so many different reasons, particularly when it's intermittent like this; it can be very, very difficult to diagnose.

Back up!

My recommendation would be that you begin, of course, by backing up.

The fact that it is working intermittently (or working more often than not) could change. This is a sign that there is something wrong and you do run the risk, at some point, of the computer not booting at all.

So the very first thing you should do is make sure that you're backing up and backing up regularly.


That aside, then I would start looking at things like overheating.

  • Make sure that the computer has enough ventilation.

  • That it's not full of dust (a very common thing that happens to computers that have been around for a while.)

  • Make sure that all of the monitor cables are connected properly.

Reseat the cards

If you're so inclined, one of the other things that sometimes helps is to unplug the computer from your power. Open it up and basically reseat all of the cards, all of the removable cards – the expansion card, the memory cards, and so forth.

Make sure you're well grounded; that there's no opportunity for static to damage anything. This is sometimes something that people have found to be helpful – some of the connections may be intermittent and it may be as simple as that causing your problem.

RAM diagnostic

I would run a RAM diagnostic after the machine is running again. Just to make sure that all of your RAM is operating properly.

The problem with RAM is that a single bad bit in RAM can sometimes manifest in these completely random ways.

Tech help

Outside of that, it starts to get really difficult to nail down. It might be time to pull in a technician to see if they have any additional ideas.

But, those are the kinds of things I would have you do, at least to start to diagnose this problem.

  • Fundamentally, it's as simple as your computer is crashing randomly during boot process.

Article C5603 - July 19, 2012 « »

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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.

Not what you needed?

John O'Meara
July 20, 2012 8:46 AM

I wouldn't have thought this possible, but it happened recently - a defective (and very new) video cable. So swapping the video cable should be added to the troubleshooting list.

Scott Currier
July 20, 2012 1:19 PM

I have the same thing happen on my Dell here at work which is running Win 7. The reason appears much more benign, the power setting turns off the display after 10 minutes of inactivity. In WinXP when I used the same setting the display would just go black. Now with Win7 is displays the no-signal error message. No big deal. Just hit a key or move the mouse and it comes right back on.

John Hess
July 20, 2012 7:56 PM

Gosh, I'm shocked; my 5 month old HP Pavillion has been doing that on reboot since new. I just thought it was part of the process. Should I have HP fix it? (I did get an in-home service contract.)

If the machine is booting normally, then I'd say no. It just means that for some portion of the boot process the computer is not sending a signal to the monitor.
Fred Wortham
July 27, 2012 1:50 PM

This has been happening to me for the year I've had Windows 7 installed (no new computer, just the retail OS). But, everything works like gangbusters before and after boot up, so, I just attributed it to a quirk of the Win 7 boot process, or that perhaps my specific brand of monitor (acer) or the video card itself (evga Nvidia 8400) was reacting to something quirky about the video signal.

I had the same brand of monitor and the same video card for a short time while I was still using XP, and that didn't happen. But, again, everything else works just fine, and no malware, so I s'pose it's just another Microsoft weirdness!

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