Undervolting is done in order to conserve power, particularly in laptops and other mobile devices, where energy comes from a battery and thus is limited, or in rare cases, to increase reliability.
However, changing the gate's voltage requires charging or discharging the capacitance at its node.
This results in a lower RC time constant for quicker charging and discharging of the capacitance of the subsequent logic stage.
Video cards and motherboard northbridges are components which frequently require hardware modifications to change supply voltages.
Moreover, there is also a static leakage current, which has become more and more accentuated as feature sizes have become smaller (below 90 nanometres) and threshold levels lower.
Low voltage modes are used in conjunction with lowered clock frequencies to minimize power consumption associated with components such as CPUs and DSPs; only when significant computational power is needed will the voltage and frequency be raised.
There are complex tradeoffs to consider, which depend on the particular system, the load presented to it, and power management goals.
The 167-processor AsAP 2 chip enables individual processors to make extremely fast (on the order of 1-2ns) and locally controlled changes to their own supply voltages.
Another approach uses per-core on-chip switching regulators for dynamic voltage and frequency scaling (DVFS).
[2] Unix system provides a userspace governor, allowing to modify the CPU frequencies[citation needed] (though limited to hardware capabilities).
Reducing the voltage supplied to the CPU below the manufacturer's recommended minimum setting can result in system instability.
There are also longer-term concerns: various adverse device-level effects such as hot carrier injection and electromigration occur more rapidly at higher voltages, decreasing the lifespan of overvolted components.
In order to mitigate the increased heat from overvolting, it's recommended to use liquid cooling to achieve higher ceilings and thresholds than you normally would with an aftermarket cooler.
Also known as 'all-in-one' (AIO) coolers, they offer a far more effective method of unit cooling by relocating heat outside a computer case via the fans on the radiator whereas air cooling only disperses heat from the affected unit, increasing overall ambient temperatures.