Underclocking, also known as downclocking, is modifying a computer or electronic circuit's timing settings to run at a lower clock rate than is specified.
Underclocking refers to alterations of the timing of a synchronous circuit in order to lower a device's energy needs.
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.
Newer and faster 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.
[1]) will underclock themselves automatically under a light processing load, when the machine BIOS and the operating system support it.
In supported processors, using cpufreq to gain access to this feature gives the system administrator a variable level of control over the CPU's clock rate.
Underclocking can be done manually in the BIOS or with Windows applications, or dynamically using features such as Intel's SpeedStep or AMD's Cool'n'Quiet.
Even when the system is busy, a large amount of time is usually spent waiting for data from memory, disk, or other devices.