No he isnt overclocking it, since PC2-6400 runs max of 400MHZ and his bus speed is only at 332 there.
Make SURE that your memory is running 1:1 that gives the best overclock. If you havent already you may want to try upping your VCORE. Up it .05 to .1 and put that BUS SPEED to w/e you wanted it at to get 3ghz, load up windows and now see if its stable.