Overclocking is the process of forcing a computer component to
run at a higher clock rate than designed or designated by the
manufacturer.
Overclocking is usually practiced by PC enthusiasts in order to
increase the performance of their computers. Some hardware
enthusiasts purchase low-end computer components which they then
overclock, thereby attaining performance of a high-end system,
while others will overclock high-end components, attaining levels
of performance that surpass the performance of the newest
generation of computer hardware.
Commonly overclocked components include: processors, video cards,
motherboard chipsets, and RAM.
http://en.wikipedia.org/wiki/Overclocking
