Abstract: The present invention is a method and system for flexibly and efficiently providing electrical power within a computer system. The present invention comprises an isolated ground reference direct current power supply, including an AC/DC converter that transforms alternating current into direct current and an isolation component that provides DC voltage outputs. At least two of the DC voltage outputs have ground references that are isolated from one another in a manner that is compliant with IEEE 1394 requirements. One of the ground references is supplied as the chassis ground for the computer system and is coupled to most of the components of the computer system. Another of the ground references is isolated from the chassis ground reference and is coupled to the physical layer of an IEEE serial communications circuit. A DC to DC converter is used with the power supply to generate the isolated ground reference for the physical layer.