Voltage Regulator Module

Motherboards have a voltage regulator in order to reduce the voltage supplied by the power supply (5 V or 3.3 V) into the voltage required by the CPU.
At the time of socket 7 and slot 1 motherboards manufacturers decided to put a connector called VRM on the motherboard. In the future, if a new CPU was released with a voltage that the motherboard couldn’t supply, you could simply install a VRM module for replacing the motherboard voltage regulator and supplying the CPU with its correct voltage.

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Figure 1: VRM module.

Figure 2: VRM module installed on a motherboard supporting this feature.

This system is not used anymore, since voltage regulators used on motherboards nowadays are more “intelligent”, supplying more voltages than socket 7 and slot 1 motherboards could and being BIOS-programmed (in the old days voltage configuration was done through a series of jumpers located on the motherboard). This allows the motherboard to supply the correct voltage to any CPU even those not released yet. When the PC BIOS (actually, POST) identifies the installed CPU, it automatically configures the voltage regulator to supply the correct voltage required by that CPU. On some motherboards it is possible to configure manually the CPU voltage through setup (this is usually done to increase overclocking; regular users don’t need to mess with this).