A voltage regulation system, method of operation and multiple processor apparatus employing the system or method. The voltage regulation system includes a plurality of voltage regulation modules (VRMs) coupled to a plurality of processors, each one of the VRMs is dedicated to only one of the plurality of processors wherein a processor is powered down in response to a failure of its respective dedicated VRM.

In one embodiment, a circuit to indicate a match between a user-selectable power setting and an input voltage, comprises a first circuit node connected to a power source at an input voltage level, a second circuit node, a switch to switch the first circuit node and the second circuit node between a first position associated with a first voltage and a second position associated with a second voltage, and a first indicator coupled to the first circuit node and the second circuit node and activated when the switch is set in a position that corresponds to the input voltage level.

Apparatus for automatically selecting one of two or more available power supply voltages for use as a main power supply of a PCI adapter is described. In one embodiment, a power supply selector is designed such that the presence of a positive voltage at a Vaux input thereof prevents power at a Vcc input thereof from driving a main power supply input to a PCI adapter. Conversely, the absence of a positive voltage at the Vaux results in the main power supply input to the PCI adapter being derived from the Vcc input. In an alternative embodiment, jumpers are provided for enabling a user to select which power supply will be used as the "default" power supply for the adapter.