a problem after my vga installation

Hello,
I bought my new Twintech Nvida GTX570 last week and even though I installed everything correctly I have a major problem going on. At first it did it in Dragon Age 2 but after a restart it did it in Crysis2 demo and Bad company 2. While I play the games the screen freeses and the sound gets into a loop, after that I can't do anything else but restart. I've checked my gpu's and cpu's temperatures and they are fine. I'm thinking that my PSU may not be able to handle it. Best case scenario, the pc needs a format for the new nvidia drivers to get installed.
Any suggestions or anything that I might have missed?
Specs:
CPU Type:QuadCore Intel Core i7 920, 2666 MHz (20 x 133)
Motherboard Name:Asus Rampage II Gene (1 PCI, 1 PCI-E x4, 2 PCI-E x16, 6 DDR3 DIMM, Audio, Dual Gigabit LAN, IEEE-1394)
System Memory:6135 MB (DDR3-1333 DDR3 SDRAM)
Video Adapter:NVIDIA GeForce GTX 570 (1280 MB)
PSU is a 650w Silverstone