Display distortion

[Epyonmk3]

I have a problem with my wife's computer that is bugging me no end, as I have tried all fixes I know and there has been no change.

The computer apparently froze today while I was away, and so my wife did the fix-all remedy of a hard reset. Now the display has gone strange, with ripples travelling vertically on the display. It looks like a sine wave effect with the display wobbling about 5mm from side to side. The distortion isn't as pronounced along the right edge of the display, which is useful, as I can move windows to the right to attempt reading text.

I have tried:
Resetting the monitor. No effect.
Testing a different monitor on the computer. The effect is the same, so it's not the monitor or display cable.
Resetting the computer (restart). I noticed that the problem is present straight from booting up.
Cleaning the inside of the computer of dust. There was a lot of dust in there, but it didn't fix the problem.
Updating the drivers for the graphics chipset. It's an embedded ATI Radeon Xpress 200, the same one it was built with. No change.

I'm wondering if it might be a BIOS issue, but I'm reluctant to mess with that, as reading wobbling DOS text is a nightmare.

Can anyone suggest anything I've not tried? I'm at a loss.

It might be time for a new graphics card, but I don't even know if that will fix this issue.

[Computer_Commando]

My educated guess is an unstable power supply.  All the dust you found inside the case is a clue.  See if you can blow out all the dust from the power supply.

[smeezekitty]

if its not onboard maybe graphics card needs a reseat
or maybe the moniter sync pin is broken, bent or not working

[Epyonmk3]

Where would I find this 'monitor sync pin' you mentioned? Is it part of the display cable? I changed the cable already and determined that it's not the monitor or the display cable. A different monitor and different display cable produced the same issue.

I'm unsure how dust in the power supply could produce this display distortion, but I've blown all the dust out anyway.

I think it might be time for a new graphics card. This one is onboard, old, and unable to deal with most of today's games.

More information about this system, in case it helps diagnose the problem:
OS: Windows XP Professional edition, 32bit.
RAM: 1GB.
Processor: AMD Athlon 64 3500+

It's a basic eMachines desktop we bought 3 years ago, and haven't upgraded since.

[smeezekitty]

is there any junk in the moniter connection?
make sure the 20/24 pin PSU connection to the mobo is tight
also how does the screen look during POST?
only hope your mobo hasnt gone bad

[Epyonmk3]

I'll check the PSU connection. Thanks for the suggestion, I'll let you know how that goes.
There is no junk in the monitor connection.
The screen has the same distortion during POST.
I hope my mobo hasn't gone bad also. I've heard that resorting to a hard reset can (rarely) cause problems, but what else can you do when your computer freezes up?

[smeezekitty]

the worst that can happen from a hard reset is hdd damage
if after checking what was sugjested earlyer
disconnect the hdd
and see if it still does it

[Epyonmk3]

PSU connection checked and reseated.
Hard drive disconnected, computer had the same issue upon boot. Hard drive reconnected.
As a last resort, RAM reseated.

Still no change. I'm going to bed and gonna try again tomorrow.

[smeezekitty]

have a video card you can barrow?
if so plug it in
if it still does it PSU or mobo is shot
otherwise the onboard is bad

[Epyonmk3]

Thanks to everyone who helped. The onboard GPU was indeed bad. I got a new graphics card (not top of the range, just something functional) and it fixed the problem.

[Geek-9pm]

Thanks to everyone who helped. The onboard GPU was indeed bad. I got a new graphics card (not top of the range, just something functional) and it fixed the problem.

Another case of the last thing you try...