Comp. corrupting video card

I have an ATI VisionTek 1550x series card with 512mb. I was having problems with the graphics and the computer crashing during gameplay, stating a graphical error. I sent the card in and VisionTek agreed that the card was corrupted. They tested and sent out a new card. 24 hours after placing the card in the computer the same problems started up again. VisionTek will send another new card, but they want to be sure it is not a problem with my computer. They think that my computer may be somehow corrupting the video cards. Originally my comp. has a Nvidia gforce 6200 card, built into the motherboard. But it was disabled when the new card was purchased. I am not sure if this could still be causing problems. I called Best Buy since that is where I purchased everything and they said it would cost 150 to do diagnostics, not to fix it. So, I am wondering if there is anyway I can test my computer my self, or if it is something that will have to be taken in. Any help would be appreciated. Thank you.

 

I think you were probably just sent another bad card, this happened to me when eVGA sent me a 7900gs to replace my dead 6600gt.. the 7900gs was DOA and I had to wait for them to replace it again. the only way your computer could be causing problems is if you have something overclocked or if the power supply is putting out the wrong voltages.. If it was the power supply you would probably have problems other than just the video card, so I doubt it.