My Screen Turns white
 

Hi guys im here again to ask your help
I returned the last videocard and got a new evga gtx260 yesterday.I was stressing the card using GPU CAPS Viewer then i got a white screen at first then a pixelized screen. I restarted the system and the motherboard beep 1long 3shorts= videocard. After that I restarted again and POST properly. Is my videocard defective again or is it just the heat?