AC-DC server power supplies: making the leap to higher efficiency

Basic 1u and 2u ("desktop-derived") servers represent the vast majority (5 to 8 million units) of total servers in use in the U.S. They also dominate the energy consumption resulting from all types of servers (about 11 billion kwh/year) in the U.S. About a quarter of this energy can be saved by improving typical server power supply efficiency at part load from an average of 66% to more than 80%. This paper summarizes our measurements of 1u and 2u server power supply efficiencies, estimates savings from increasing average efficiency, and describes opportunities to use industry specifications, federal labeling, utility incentive programs, and targeted procurement efforts to encourage sales of more efficient server power supplies