Vertical bars display: Could this be a power supply problem?

About 6 minutes after bootup, the image on my monitor starts to deteriorate. First the cursor gets an unnatural shadow. Then several vertical bars snap across the screen, at precisely spaced intervals, the full height of the screen. Within these bars the image appears to "crawl".

Switched out the monitor, same effect.

When the system is allowed to cool off, it reboots with a normal image.

Opened the box and checked the fans. I have three: power supply, graphics board, and processor. All three spin, but the box has been very dirty. I vaccumed it. We have a renovaton project going in the room where the computer sits, so it has been sucking dust.

The problem came on suddenly a few days ago, but it is now a permanent feature. After six minutes, the display produces these columns or bars of visual noise. Since it seems to be a heat effect, I then turn the machine off.

The system is a 3-year old Dell Dimension 8250. The supply is a 250 W HP-P2507F3C.

Anyone seen this effect before?

Possible this is hum? Blown electrolytic capacitor maybe? Or should I look at the motherboard or graphics?


Many thanks for your insights.

Regards, Michael

Thank you for your analysis. The graphics card is an ati Radeon 9700, not clear whether it is "Pro" or not. Memory on the card is 128.

The graphics card fan does work, and the bars are a new problem that came on -- or at least became apparent - suddenly.

Hi. I swapped the 9700 for an ati card in our other Dell (a 7500, probably).

So far, after 28 minutes of continuous operation, no vertical bars have appeared.

I will keep testig, but it looks just now as though it will turn out that the 9700 graphics card was responsible. I think maybe it overheated, fan and all, because of the heavy dust in here lately (sanding and painting and general uproar.)

Thank you very much for pinpointing the ati 9700.

Michael

Great .. Well I would still keep the Radeon 9700(and I'm assuming its a pro after some research) , but add a ducted cooling method or slot cooler, just something to get the hot air away from the card.

Duct Mod, for CPU and Video Card (Possibly many other things)
http://overclockers.com/tips1187/

Or a type of slot cooler that looks something like this:
http://www.coolerguys.com/840556017165.html <--Btw cheapest one I found

Or Maybe Try Both? ...