Dell proudly announced it's the first in the industry to achieve 80 PLUS Gold-certification for a server power supply. This means this PSU has a 92 percent minimum efficiency at 50 percent of rated output:
The 80 PLUS certification enables our customers to compare and contrast power supplies based on criteria from Energy Star and the Climate Savers Computing initiative. Our new 80 PLUS Gold power supply meets July 2009 Climate Savers targets for servers more than a year ahead of schedule, which require 92 percent minimum efficiency for the power supply unit at 50 percent of rated output. Earlier this month, we became the first Tier-1 computer manufacturer to achieve 80 PLUS Silver-certification for our client desktops. The 80 PLUS Silver certification is up to 8 percent more efficient than what is required to meet Energy Star 4.0, up to 3 percent more efficient than the Energy Star 5.0 draft and also meets the July 2009 PC requirements outlined by Climate Savers.
A test report from 80 Plus shows the Dell PS-2901-1D-LF 2U Custom 900W PSU has a typical efficiency of 89.40%! At a load of 10% the PSU has an effciency of 85.08%, at 20% it climbs to 89.98% and at max load it has an efficiency of 90.18%. The highest efficiency is reached at a load of 50%, the model reaches a stunning efficiency of 92.39%.