well it's kinda hard to describe for you specifically, because almost every BIOS is different but It is generally found under chipset features.
P.S. I really recommend that you read a little more up on overclocking your Processor! I am a semi-intermediate overclocker and am currently building a custom water-cooling rig for my PC and overclocking is not an exact science, so I recommend you look before you leap.
Processors can get expensive after melting down 2 or 3 of 'em
"Speaking from personal experiences and those of friends"