Overclock
Sometimes abbreviated as OC, overclock is a method of setting a computer to perform faster than its advertised speed by setting or changing jumpers, dipswitches, CMOS settings, firmware updates, or using software utilities. Overclocking allows users to get a small increase (sometimes large) in performance boost and is commonly performed on CPUs or Video cards.
It is recommended that overclocking be performed only by advanced computer users or users aware of its risks. When overclocking a computer it is possible for the computer to experience random errors or lockups related to heat. It will void your warranty on the hardware device and possibly the computer or motherboard. Finally, overclocking can sometimes damage and even destroy computer components.
Also see: CPU definitions, Hack, Multiplier, Optimize, Processor throttling, Tweak