Games freezing and then loading wrong textures

[PhikMan]

Hey, I'm having a very strange problem with my new gaming rig. When i play games, they will run fine for a while, but then they would suddenly freeze for a moment then load the wrong textures for the game, most of the times making it un playable.

what im running:
Intel core 2 quad q9450
4 gig corsair dominator ram running at 1066 MHz
inno 3d 9800 gtx overclock edition
320 and 80 gig hdd in sata 2
700 watt psu
asus maximus formula motherboard

whats even stranger is that if i move the video card to another pcie x16 slot on the motherboard, the games will run fine for a day or so, then go back to crashing.
Ive stress tested each chip of ram, checked each hdd for errors, added extra cooling to vid card, done a whole system rebuild, updated bios, updated every driver i can think of. i just cant get them to run properly.
the video card is running at temps of around 64 degrees Celsius during games and idle at 45.
please help, its really annoying when you try to play games!