Overclocking is the process of configuring a computer processor or other electronic circuit to run faster than it was designed to. Overclocking allows a computer to be faster and more responsive. Overclocked processors tend to use more electricity and make more heat than those running at their intended speed. It is often necessary to install a better heat sink to avoid overheating the processor. If a processor is overclocked too high, it can damage the processor or make the computer unstable. Increasing the voltage to the processor can allow it to be run at even higher speeds where it would otherwise be unstable, but this carries an especially high risk of damaging the processor.
Overclocking is usually done in the computer's BIOS setup utility. Most brand-name computers such as Dell, HP, and others do not allow overclocking in the BIOS setup utility, but custom-built computers usually do. It is also possible to do the opposite, called underclocking, where the processor is run at a lower speed than intended. This may be done to extend battery life and reduce heat output. Underclocking will not usually damage a processor and may in fact make it last longer. Some processors automatically underclock themselves when the computer is not doing a lot of work.