It would be pretty unusual for a CPU overclock to cause artifacts (more likely to be a faulty/overheating gfx card) or for a Q9550 to be unstable at 3.1GHz, even on stock volts. Most Q9550s will run happily at 3.6GHz with only a small voltage increase and a few push past 4GHz. Ur CPU is definnately not too old, especially if ur playing BF3 as the type of CPU (including overclock) does not seem to have any effect on frames per second in BF3.