I installed my new graphic card gt 640 a few days ago and it is making lines appear across my screen no matter what I'm doing! The lines will stop for a few seconds but always come right back. I started with windows xp and upgraded to windows 8 hoping that might be it but it's still doing the same exact thing. Only time I was able stop it was by changing to 16bit color while still on xp. I've updated to the current drivers from nvidia. I've reinstalled the driver three times and no luck. Is the card bad? Anything else I can try?
Mobo is a asus p5q with intelcore 2 duo wolfdale 3.0 4gb ram
500w power supply windows 8 32 bit