Well, this problem actually came before when I tried the 260 drivers a long time ago but it went away after a fresh reformat and me going back to the 197.45 drivers.
Now it's back.
It started a few days ago when I upgraded the hard disk on the box to a larger one. Everything worked fine at first after the upgrade and disk imaging, but then my fingers got itchy and I decided to try the 275.33 drivers on the box.
Afther that, this happened, as it did when I tried the previous 260 drivers:
Every Steam game is like that- It would have this green flicker and banding. Ironically I could not reproduce the problem in the NVidia control panel or the Freestone Video Card Stability Test.
I have tried recopying the image from the old hard disk (which I still have), but the problem appears to have stuck. Even with the new hard disk wiped and the old hard disk re-imaged onto the new, the problem persists.
I noticed that Asus has a BIOS upgrade that purportedly fixes the issue, and my card is among those on the list (Running one pair of ENGTS250 Dark Knight 1GB in SLI mode), but the update won't install- it just says that my card doesn't match the VBIOS.
Anyone know how to fix this? I really don't want to reformat the machine and go through a tonne of updates.
Nevermind, the problem has went away again. Apparently the system doesn't like the fact that I have a 3.5" to dual 2.5" hotswap hard disk cage installed. I replaced the aging 120GB hard drive with a 320GB laptop hard disk instead, and bought the cage because installing a hard disk in this case is a major PITA (involves pulling out every single card and RAM bars from the system). Connecting the SATA and power leads directly to the hard disk solves the problem, unbelievably.
*sigh* Looks like I'm going to have to figure out how to mount a 2.5" HDD on this case without using the hard disk cage.