my specs:albatron 8800gt 512 mb. i got accelero s1 + 120mm fan blow air in to the gc. i've modded the volt to 1.1v thru bios mod. when i try 700/1800/1000 in ati tool for few hours there's no artifacts or any problem. so does in game like DMC4,cod4,bioshock. but until one day i play pes2008,when i in a match and exactly after i score a goal,in the cinematic part,suddenly the artifact flying around my screen. i had to reset my pc. the i downclock to 650/17**/1000 but still the artifact is there. only when i down the memory clock to 950,i can play happily ever after.this do happen in Guitar hero 3. i don't know what's wrong. my gc temp:idle 45 load 52+ thanks.