I7 system randomly freezing

Hi everybody!
I recently built a new system from the following components:
CPU: Intel i7 920
MB: Asus P6T Deluxe V2
RAM: DDR3 Corsair Dominator 1600mhz (3x2GB)
PSU: Corsair 750TX
GPU: Geforce 8800GT

The problem is that the system is freezing at random, and this can be playing a game, watching a video, surfing the net, or just idleing. The screen freezes up, and the keyboard too... The only way of shutting it down is holding in the power button. The weird thing is that if i have a program like Ventrilo (A program for talking with other people over the internet), i can still hear them talking even though the rest of the computer seems to be frozen. I've tried to set up the rams voltages manually, and take them out piece by piece, that doesn't work. I've tried a new HD, that doesn't work. Have any of you had similar setups with this problem, or do you have some tips on how to fix it? Hope you can help!

Best regards sunek.

You might think about an RMA if you think you might SLI in the future.