Hey Buan,

This is my setup

Intel E6750
AtI 3870
750W PC Power and Cooling
2 gig Ram G-skill 4-4-4-12
Asus P5K-E WIFI/AP

And I also have the same issue, and I have come to the conclusion it if the video card not handling all the accounts. I did this by tweaking the card.

First I downloaded RivaTurner latest, and then OC the card to 850 core and 1280 memory, then boosted fan speed to 70% and close to no glitches but pretty annoying with the fan being so load.

Not to disappointed since I did plan to use Crossfire in my system just waiting for some more cash. I would be pretty pissed though if crossfire didn't help with the tearing and graphical glitches.

Hope you read this and confirm what I also went through and pinpointing the problem.

Good luck mate, if your not going CF like me then might as well sell your card and get a 8800GT if a single can run it.