Little bit of an update... It must have been the clocks that I set it at. B/c I kept it at 730/1000, then did the artifact scan in ATITool...not 30 seconds later I started getting terrible artifacting. Downclocked it to 720/1000, and it didn't artifact. Played a few rounds of FEAR in some of the more fast-paced levels...and it worked fine... I'll try again tonight (Friday night...more people will probably be playing, heh).
Odd though, that I could keep it at 730/1000 and play Crysis just fine without any artifacts for hours o.O.