To conserve power and manage heat, many laptop and desktop processors have a power management feature that software (usually the operating system) can use to adjust the clock speed and core voltage dynamically.
, which depends on the geometrical shape of the FET's channel and gate and their physical properties, especially capacitance.
The trend towards lower supply voltage therefore works against the goal of high clock speed.
Overclocking a processor increases its clock speed at the cost of system stability.
[1] Overvolting generally involves running a processor out of its specifications, which may damage it or shorten CPU life.
A dual-voltage CPU uses a split-rail design so the processor core can use a lower voltage, while the external Input/Output (I/O) voltages remain at 3.3 volts (or 5 volts for older CPU's) for backwards compatibility.
Dual-voltage CPUs were introduced for performance gain when increasing clock speeds and finer semiconductor fabrication processes caused excess heat generation and power supply concerns, especially regarding laptop computers.
VRT is a feature on older Intel P5 Pentium processors that are typically intended for use in a mobile environment.
All Pentium MMX and later processors adopted this so-called split rail power supply.
As semiconductor technology has advanced, functions such as CPU cores, memory controllers, PCIe controllers, and, in some cases, integrated graphics, have been consolidated into a single CPU package.
However, despite the overall reduction in transistor size, not all voltage requirements scale down proportionally.