look at ur cpu's box, look for the "batch #", if it says L624A264, then u have a crap cpu like me ...i confirmed it with another one from xs. he's L624A264 E6400 cpu tops out at 425fsb 3.4GHz, and he said 420fsb is good for 24/7.
batch # is important, a lot of peopel with L625xxx been doing...