Display randomly loses signal

[CurseTheSky]

My brother's computer has recently been running into problems. It worked fine for several years, but recently his monitor will suddenly go black, then display the "no signal" alert. Usually restarting the computer fixes the issue. Sometimes it happens 2-4 times a day, and sometimes he goes several days with no issues.

Specs:
Core 2 Duo E6600
4GB Corsair DDR2 800
ASUS P5B Deluxe (P965)
EVGA 8800 GTX (worked great in my computer, before I bought my GTX 285)
Thermaltake Toughpower 650w
200GB Hard Drive
Thermaltake Tsunami Dream (should have plenty of cooling)
Windows Xp Home 32-bit

When the problem first started, I though it was a software / driver issue, so I did a fresh format / install of Xp, and downloaded the latest driver from nVidia (either 180 series, or 190 series... maybe 186.xx?). It's still happening, and usually occurs when he's playing a game (usually WoW, so it's shouldn't be heating up too much). When it happens, I believe he can switch the input over to HDMI and use his PS3 that's also hooked up to the monitor without any issues, though I'm not 100% sure.

Any idea what the problem might be? At this point I'm suspecting PSU failure, but I don't have any definitive proof.

 

[lopri]

How old is the monitor and where is the brightness set at?

 

[imported_Scoop]

Eliminate the obvious culprits, GPU and monitor first by trying different GPUs and monitors. If it's not either one, I'd suspect the motherboard.

 

[zagood]

Sounds like it only happens when it's under stress. Use 3dMark06 to try and replicate. I think it's the video card, but I agree it also sounds like PSU. With the vague symptoms though could be CPU, ram, motherboard, all sorts of stuff.

Also If you can't replicate it outside of WOW that's going to be really hard to track down.

Whatever you do, make sure you're running some background monitoring with logging on - so if it crashes you can check temps etc. when you boot back up. RivaTuner is really good for this.