This trade study compares the cost, weight, volume and reliability of a power subsystem for an avionic processor. It considers a range of options from a centralized power subsystem to a distributed subsystem with an intermediate bus. The centralized approach was found unsuitable for the lower voltage logic devices that will come to the market over the next few years, a distributed approach will be required. An intermediate voltage bus is preferred over prime power distribution due to safety, high voltage insulation and failure modes effects. Choices of the intermediate bus voltage favor lower voltages which allow the use of buck regulators rather than a transformer coupled approach. An intermediate voltage system using buck regulators provides: 50% cost savings; 20% weight reduction; 25 volume reduction; and 75% reliability improvement when compared to a higher (50 V) distribution voltage.