Freezing Help ???

[chrisbram]

I am so sick of my pc freezing up and cant seem to find out why its doing it. It mainly happens during playing games (depends which game) some games never freeze some always freeze. Sometimes it freezes straight away sometimes after an hour sometimes not at all. It is usually just games that freeze but I recently installed windows 7 beta on a second drive and sometimes that freezes just using internet explorer. I have the latest video drivers , I have ran memtest on my ram , i have checked the voltage and timing on ram , i have checked for card overheating , everything seems fine but the freezes dont stop happening. Anything else could be causing this? I have also made sure my display is set to the monitors resolution 1680 x 1050. One game that froze alot was world of warcraft but i ran it in opengl and that fixed the problem. I have tried to run other games using opengl the same way i ran wow in it but it hasnt made any difference. If anyone has any ideas ill try anything.

Computer specs:
Q9550 2.8ghz Qaud core (no overclocking)
4gig DDR3 1333MHZ ram
Asus Striker II extreme MOB
1000w Antec Quattro PSU
GTX280 video card
Windows Vista Ultimate 32bit
Second boot on Windows 7 32bit Beta