Comments on: Computer screen blinking on and off

Question: Computer screen blinking on and off

Harald74 — Thu, 29 Jul 2010 00:40:36 -0800

My secondary PC screen is blinking on and off when certain events occur.

OK, so I cannibalised an older PC here at work to get a graphics card with dual DVI out. The previous one was a gForce-based one with one DVI and one VGA output. I removed all nVidia drivers and applications, and installed the correct drivers for the "new" card, which is a Club3D Radeon X1300PRO 256MB CGAX-HP136. I grabbed the drivers and extras from ATI's site and installed them.

I got my new setup with two screens to work perfectly from the start, but with 1280x1024 @ 75 Hz resolution. As soon as I switched to the native display resolution of 1600x1200, which the graphics card could run at only 60 Hz, the secondary display started blinking on and off at approx 1 Hz. I procured a third screen of the same kind (HP LP2065) to try out, and checked and switched cables, but the problem persisted. A Google search turned up someone who had a similar problem which was cured by killing the "ATI Hotkey Poller" service in XP. For me this fix stopped the incessant blinking, but the screen still blinks off for a split second about every minute or so.

And there's one more sympton: When I move a Windows Explorer window unto the secondary screen, and that windows is either bigger than about half the screen area, or I enlarge it to that size while it's on the secondary screen, the scrren also goes black. Shrinking the window back below the threshold gives me my screen back.

I run Windows XP SP2, which is mandated by my workplace, so I can't really change that. But I'm open to other suggestions.

By: Rendus

Rendus — Thu, 29 Jul 2010 01:10:33 -0800

Try setting the flaky display as the primary display and see if that helps any.

By: Harald74

Harald74 — Thu, 29 Jul 2010 01:41:14 -0800

I tried switching around the primary display, but the symptoms stayed the same.

By: 3mendo

3mendo — Thu, 29 Jul 2010 05:02:15 -0800

as a point of reference, the secondary display attached to my ati mobility x1400 does sort of blink* from time to time, as well as display artifacts during intense scrolling.
* well, it's more like the bottom left part of the secondary screen displays an obviously misinterpreted bitmap for a split second.
Have you tried running some live linux distro, possibly installed to a usb drive so you can install appropriate drivers (in case they exist..)? You could rule out hardware problems in case it worked.
another voodoo level test to run: can you use a different cable?

By: NBJack

NBJack — Thu, 29 Jul 2010 05:17:21 -0800

Sounds like there may be insufficient power to drive your video card when both monitors are connected. One way you might be able to check is to trying running a high-load application (i.e. Prime95) and see if behavior changes; this should force parts of your box to draw more.

Otherwise, you might have a card with some bad video memory. This tool may be able to root it out. That would explain the scrolling artifacts.

If none of these seem to work, you could also try monitoring temperature. High heat is the enemy of a stable system. I prefer SpeedFan(the download link is hidden a bit).

By: Harald74

Harald74 — Thu, 29 Jul 2010 05:44:02 -0800

Several good suggestions here.

I've tried swapping the cables, getting new cables, making sure they are secure etc. No difference.

Stressing the CPU did absolutely nothing. Regarding heat, the computer case is currently open and the symptoms are present from when I first boot the PC. I'll archive this possibility under "unlikely" for the time being.

I'll run the video card memory test when I leave work later and check the results in the morning.

By: Harald74

Harald74 — Mon, 30 Aug 2010 02:45:11 -0800

No memory faults, as it turned out. I'm stuck running the secondary display on a lower resolution.