Graphics problem

[Xenarious]

I recently moved to my new flat from my home for university. When i arrived and turned on my pc the monitor had no signal and was just blank, displaying a white square, which im assuming it does when there is something wrong with the graphics card.
I tried swapping round graphics card with my mates pc, he has an ATi 9800, I have a X800 Pro. Strange thing is mine works seemlessly on his computer with no problems and his works fine on mine. We then swapped them back and mine worked for a while again, but after it was working for a while i was fiddling with the sound inputs for my soundcard at the back of the PC and my computer shut down. When I loaded it up again the same problem occured. We then swapped around the cards once more and alas, they worked fine on each others PC's.
I think it could be either a problem with the AGP slot on my motherboard or a possible PSU issue, though I have a Thermtake 560w.

Any Ideas?

 

[dead1ne]

From what you described it seems like the only problem is that you aren't installing it securely. It could just be that your motherboard connector is just worn but make sure you push it all the way in(if there is a latch it should snap shut) and that you screw it in tightly.

 

[Xenarious]

Beleive me, I have done that and it feels normal. Ironically, I felt that the 9800 wasnt in as hard and securely as the X800 Pro.

 

[Xenarious]

No one have any other ideas?