I have two cards, 5850 and 7950. I'm using 5850 for primary and when I got up this morning, I noticed that there is no display on monitor. I pluged it to 7950 and nothing changed (plus it seemed harddrive didn't response). I restarted the PC, everything works well with 5850 but same with 7950. There is display on both BIOS and safe mode from 7950. So I decided to uninstall and reinstall the drivers. When the installing is nearly complete, the screen went black again. So this is a technical problem? What should I do? (I have been using the both cards for mining about two weeks). I have Win 7, 750W PSU. Thanks by advance.