Core 2 Duo E6420 running slower?

[meat_helmet]

And what STE said, is what I should to to overclock it?

Well u can if it suits, provided you cpu is unlocked downwards. It does have advantages for getting your memory at good ratios eg. as ste said, 8 X 450 would mean u might be able to run you memory at 1:1 @ 900Mhz. This will depend how well your ram overclocks of course.