We have a HP p6213w w/6G Ram, using windows 7, and added a Nvidia GForce 220 card. After adding the card, the pc would lock up during WoW gaming, with the screen going blank, and the pc would have to be turned off, then back on to restart. We added a Thermaltake TR2 600w power source and the problem stopped. After our recent system factory restore, the problems have started again, even with the current video card drivers installed. Any suggestions why this started again and how to fix it?