Strange video problem: horizontal blurring

[marshall]

Hello,

The display on an old computer of mine has suddenly started acting strangely. There appears to be a horizontal blur effect going on; for example, if I have a terminal window open, the black background darkens the picture on either side. Dark text on a light background looks especially bad: alternating dark/light bands appear, and the text has a sunken 3D look to it.

Now, I don't believe that this a software/driver/OS problem, as the same thing happens in the BIOS setup screen. It also doesn't seem to be a monitor problem, since the picture looks fine with another computer plugged in.

I guess that leaves the video card as the most likely culprit. Any ideas on why this weird effect would occur? Here are some details:

Computer: Dell Dimension XPS T550, P3 550Mhz, 128 MB RAM
Video card: Diamond Viper V770 32MB, NVIDIA TNT2 chipset
Monitor: Dell M780
OS: Debian 4.0 (Etch) with current nvidia driver. (Upgraded smoothly from sarge after the problem appeared with no effect)

Let me also mention that I didn't "touch" anything to cause the problem! I left the computer and it was fine; when I came back several hours later, the picture was messed up.

Thanks

[cohenx]

Did you add anything to your hardware that could cause radiation ?

Speakers next to your monitor, for example.

[tantoro]

Newer , more energy efficient CRT monitors are more sensitive to EMI Radiation, specifically from Power Supply's. If this is your setup. try moving the monitor or using an LCD. Try a known good monitor on this system anyway to try to isolate the issue.

Steve