i replaced my stock XT fan with a 65CFM 80mm fan on the stock heatsink, core temps are down to 55c and mem temps are at 40c. pepper went away...

i too am having a problem with artifacts, i am running a 9800XT that was serously overclocked and volt modded back in the day. Here are my system specs:
Abit NF7-S
74gb Raptor
120gb WD PATA drive SATA conversion
1gb PC3500 2-2-2-11 timmings
ATI 9800XT that is now stock
650watt enermax PSU
dvd/rw
mucho case cooling

It looks to be a core overheat problem, it looks like pepper all over the screen, and my GPU core temps never go over 65c. but this is the only game that it does it on. i play Battlefield 2 at max settings with no problems. drivers are the latest nforce2 drivers and cat 5.1's

If you need anymore information please let me know

Charlie Ridinger