once the prescott gets over 4ghz the p4c gets put to sleep
i've seen about 10 people online who have post benchmarks (maybe 3 or 4 on air) that hit 4ghz with prescotts
most seem to say d0 stepping in their posts
guess it's stepping 4 (mine is 3, refered to by slxxx)
most seem to have trouble hitting 3.6ghz let alone 3ghz without overheating (hehe)