I'm posting my issue here for lack of an Unreal 3 "Technology" sub-forum and it deals with several U3-based games, mainly Gears of War and Bioshock.
I played both games without incident on a Windows XP-based rig with my old 7900GT + 163.44 (Bioshock-specific) drivers, but then I "simultaneously" upgraded to an 8800 GT 512MB & 169.02 drivers in December, which is when I noted the following problem:
Atrifacts appear around brightly-lit street lights, neon signs, etc. There are other areas which have this type of lighting applied, but the above two examples are most obvious and occur frequently. In Bioshock this is part of the "post-processing" rendering. My guess is that it's Bloom "shading" being applied. As for typical HDR scenes - highlighted scenes (sunlight etc.) there are no artifacts.
The best way to describe the corruption is if I stand in front of a street lamp (or neon sign) in either Bioshock or Gears of War and then move slightly to either side, I see an odd checkerboard-like pattern that is the same color as the light being emitted. The problem is only visible at certain angles as all other angles the glow (bloom) appears correctly.
Here's a few pics so you can see what I'm referring to:
I searched / Googled etc. but I couldn't find any mention of the problem (of course it's not the easist thing to search for either ) Thanks for any info you may have on the topic
p.s. I haven't changed any settings in the nVidia drivers apart from triple buffering (to "on", as I almost always vsynch) and I changed the texture rendering quality from "Quality" to "Higest Quality".
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C2D E6850@3.00/ P5B-D/ 2GB XMS2-6400C4 DDR2@883/ eVGA 8800GT Bulk@675M1950/
Audigy2/ Seagate VII SATA in RAID1/ XPsp2-DX9c-nV169.02