Just thought I'd post my experience in hopes that it will help someone having problems...
I have a single evga 7900gt ko in a shuttle sn26p and an Athlon 64 X2 4200+... Set the system up a few days ago everything went without any problems.
installed the X2 driver from amd
installed the windows multicore hotfix from M$
installed 84.21 drivers from nvidia
DIDNT install the nforce IDE/storage drivers
Loaded up some games and at first glance no problems...
First, some games would run fine no problems at all, i.e. AoE III, quake 4, LOMAC, Falcon 4.0...
Then I started noticing some strangeness in CoD2 - artifacts would appear usually after about 5-10 mins, best way I can describe them would be as solid columns usually gray extending both horizontally and vertically and sometimes filling up a large portion of the screen. If I esc back to menu, wait a second then come back they would go away for a few mins. I also noticed this same type of effect in FEAR and to a lesser extent in Oblivion (which surprisingly ran pretty smoothly in comparison). Framerates were right where they should be but I was getting these artifacts...
In a couple other games I noticed something different, in dreamfall at a certain point right at the beginning the game would just lock and I'd have to hard reboot, or sometimes I would be a bluescreen then the system would reboot.
In Condemned: criminal origins the game would play without any problems, however when I'd exit the following would happen:
1. game would boot me to desktop (like it should)
2. desktop would have some distortion, black areas usually, icons missing sometimes.
3. whenever the screen would change (mouse movement, select start menu, etc) the screen would refresh (blank out for a second then reappear with same distortion)
4. I'd have to hard reboot the machine at this point
This exact same thing would happen when I tried to change my clock frequencies on the video card (coolbits reg entries) via the nvidia control panel.
SO, after all kinds of troubleshooting, trying all kinds of video drivers, reading about the massive problems on the boards that seemingly a lot of people are having, I think I have a bad card...
Turns out I installed the card in the wrong damn PCI-E slot! 8O How stupid is that? If you only have 1 card on an SLI mobo, make sure you install your card in the correct slot!!! It should be installed in the slot closest to your power supply!!
I hope this helps someone!!! But ALL of my symptoms I was having are completely gone now that I have my vid card in the right slot... go figure!!!