PC freezes and won't boot for 10 mins

[pGrim]

Hi,
My pc's been working nicely for a long time, but a few days ago while playing Oblivion the image on screen froze suddenly, displaying wide vertical lines of different colors, and the whole pc froze. I had to reboot.

Tried a different game, same thing happened after 10-20 minutes. But this time, the pc wouldn't reboot! Lights were on, hd started up, fans blowing, but the monitor showed 'no signal'. And that's it, no beep from the bios.

After about 10 minutes of cursing and the like, I tried to start it again, and this time the monitor flicked on, showing squares of different colors, but the pc didn't boot. Pushed the reset button, and voila everything starts up nice again, and no weird graphics on screen.

So here I am. At a complete loss. Can somebody help a poor bugger out? Should I chuck this thing over the pier? I don't know what to do

Ah yes, my hardware is this:

Asus a8n-sli premium
AMD Athlon 64 3500+
Corsair Twinx1024-3200XL Pro DDR 1024MB, 2x512
Corsair Value S PC3200 DDR-DIMM 1024MB, 2x512
XFX Geforce 6800GT 256
WD Caviar 250GB S-ATA
NorthQ 400Watt

I haven't oc'd anything. And the temperatures are fine I think.
CPU around 40 degrees C idle, graphics card about 60 degrees C idle.

 

[raybay]

Video graphics card has gone bad, is my guess. The vertical banding is typical of the failures we see in the XFX GeForce. Call their tech support if still under warranty.

 

[pGrim]

Thanks for the help.
I was also thinking it might be the video card, but I didn't understand why it should stop my pc from rebooting for a while.

 

[Tedster]

a failing PSU can also cause other components to fail. It would be wise to replace it also.