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My secondary screen looks like a TV with a bad signal, the screen is a bit snowy. I don't know how to describe it in my own language, so in English its even harder.

Beside the flickring the screens turns black every x amount of seconds and the screens shows a text 'No signal'. Most of the times when this happen the application that I'm using currently crashes.

This behaviour started today, before today it works all fine. I had never this problems with 11.10.

I have an ATI Radeon HD 5xxx and I'm using 12.04.

It began when I had default drivers installed. But when I installed ATI propariety drivers the problem remains.

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I'd suspect a hardware problem for your situation. A snowy picture is probably a pretty unusual result from a sofware or configuration problem. – John S Gruber May 22 '12 at 23:58
Sounds like a hardware problem, since you updated the drivers with the ATI proprietary drivers. – Thomas Ward May 25 '12 at 14:23
What is the secondary screen model/manufacturer/etc? I have seen this problem with an HD 5450 piping HDMI as secondary output to a Panasonic HDTV, on both Win/Lin -- old TV "snow" is exactly how I'd describe it as well – izx May 27 '12 at 11:44
Can you post a photo of the screen? – Alistair Buxton May 28 '12 at 20:09
up vote 2 down vote accepted

I would suggest that it is a hardware issue. To check, it might be a good idea to switch the monitors over and see if the problem is still on the same monitor or if it has moved to the other one. You should also try just swapping the cables to see if that's the problem.

If the problem sticks with the same monitor even when connected to a different output and changing the cable makes no difference then I would say there is something wrong with the monitor. Otherwise I would say it was the graphics card. But make sure you test the cable.

I get this same problem myself with a snowy effect and flickering if my cable comes slightly loose at the back. It may be something as simple as a bent pin in the cable head which isn't quite connecting properly and can be bent back (had that problem in the past too).

The software crashing is probably due to the PC thinking you've disconnected the monitor and just not handling that very well.

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This is exactly what I was going to respond with. Be sure that you swap the video cables and which port the monitors are connected to so you can discover a problem caused by a bad cable or to be sure that you narrow down the problem to the specific port on the video card. If you don't do this, you're not going to get this tracked down. I also agree that the crash is probably due to your system receiving mixed signals about its connectivity state. – Dusty W May 29 '12 at 9:21

Think this is probably a problem with hardware more than likely GPU. Could try:

  • Checking cable
  • Check both monitors for problems individually
  • Make sure your drivers are all up to date ( have they been upgraded recently )

As above a screenshot would be good to see the problem.


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