(n.) A voltage regulator is a small device or circuit that regulates the voltage fed to the microprocessor. The power supply of most PCs generates power at 5 volts but most microprocessors require a voltage below 3.5 volts. The voltage regulator’s job is to reduce the 5 volt signal to the lower voltage required by the microprocessor. Typically, voltage regulators are surrounded by heat sinksbecause they generate significant heat.
Pentium microprocessors with MMX actually require two voltage regulators — one for the internal (core) voltage, and one for the I/Odrivers at 3.3 volts.
Some voltage regulators, particularly those packaged as a voltage regulator module (VRM), are voltage ID (VID) programmable, which means that the microprocessor can program the voltage regulator to provide the correct voltage during power-up.