Hey if I was you i'd learn to OC.
It can be quite easy if you have 30 minutes or so to read through a guide or 2.
What happens if your OCed CPU becomes unstable?
What happens if your BIOS resets from accidental CMOS button push / battery loss, or a BIOS update / reset for new hardware?
*shrug, that's my view on a CPU pre-overclocked that extensively.
But yeah they either messed up, or you bumped something. I'd learn to OC either way! There is awesome power in that CPU and 4ghz makes it scream.