Editing Underclocking (section)

==Types==
===CPU underclocking===
For microprocessors, the purpose is generally to decrease the need for [[Computer cooling|heat dissipation devices]] or decrease the electrical [[CPU power dissipation|power consumption]]. This can provide increased system stability in high-heat environments, or can allow a system to run with a lower airflow (and therefore [[Quiet PC|quieter]]) cooling fan or without one at all. For example, a Pentium 4 processor normally clocked at 3.4&nbsp;GHz can be "underclocked" to 2&nbsp;GHz and can then be safely run with reduced fan speeds. This invariably comes at the expense of some system performance. However, the proportional performance reduction is usually less than the proportional reduction in clock speed because performance is often limited by other bottlenecks: the [[hard disk]], [[Graphics processing unit|GPU]], [[disk controller]], [[Internet]], [[computer network|network]], etc. Underclocking refers to alterations of the timing of a synchronous circuit in order to lower a device's energy needs. Deliberate underclocking involves limiting a processor's speed, which may affect the speed of operations, but may or may not make a device noticeably less able, depending on other hardware and desired use.

Many computers and other devices allow for underclocking. Manufacturers add underclocking options for many reasons. Underclocking can help with excessive heat buildup, because lower performance will not generate as much heat inside the device. It can also lower the amount of energy needed to run the device. Laptop computers and other battery-operated devices often have underclocking settings, so that batteries can last longer without being charged.

In addition to providing underclocking features, manufacturers can choose to limit the capability of a machine in order to make it more efficient. Reduced instruction set computer (RISC) models can help makers build devices that work on less power.

===Graphics cards===
Underclocking can also be performed on [[graphics card]] processor's GPUs, usually with the aim of reducing heat output. For instance, it is possible to set a GPU to run at lower [[clock rate]]s when performing everyday tasks (e.g. internet browsing and word processing), thus allowing the card to operate at lower temperature and thus lower, quieter fan speeds. The GPU can then be overclocked for more graphically intense applications, such as games. Underclocking a GPU will reduce performance, but this decrease will probably not be noticeable except in graphically intensive applications.

===Memory underclocking===
Newer and faster [[random-access memory|RAM]] may be underclocked to match older systems as an inexpensive way to replace rare or discontinued memory. This might also be necessary if stability problems are encountered at higher settings, especially in a PC with several memory modules of different clock speed. If a PC processor is underclocked, and the clock factor or multiplier (the ratio between the processor and the memory clock speed) is unchanged, the memory will also be underclocked.