For any doubters out there...THIS WORKS!! I too was skeptical, but I figured *** do I have to loose? My card is 4 years old (and the PC warranty is over) and just last week started with the artifacts BS. I followed the directions here and on other sites and it worked like a charm!
Basically remove fan and plastics (that are removable), clean up residues, bake at 385 degrees F for 10 minuets (did the trick for me). Cool for 30 minuets, put down new thermal paste reassemble and good as new. I did test it quickly for post and artifacts before reassembling (just in case it didn't work and might need to bake longer). I am using the card now! It's an 8800 GTX and reads as such in Device manager (the yellow error is gone). Tested the Windows rating and it actually rates a littler higher than before. Thanks for the info and idea!