When Energy Star 4.0 went into effect last year, it seemed to set a rather high bar for power supplies: In order for a computer to meet the standard, it needs a PSU with a minimum efficiency of 80 percent. But hardware vendor Dell already appears to have an eye on the next version of the Energy Star specification, which is slated to go into effect in July of 2009.

Over the past month, however, Dell has set a couple of new bars for PSU efficiency, unveiling the first 80 Plus Silver-certified PSU for desktops and just today announcing the first 80 Plus Gold-certified PSU for servers. The more efficient a power supply is, the less energy it wastes transforming incoming AC power into DC.

The 80 Plus performance specification is based on established criteria from Energy Star and the Climate Savers Computing Initiative (CSCI). It requires power supplies in computers and servers to be deliver 80 percent or greater energy efficiency at 20 percent, 50 percent, and 100 percent of rated load with a true power factor of 0.9 or greater.

Dell's Gold-certified PSU, the PS-2901-1D-LF, achieves 92 percent minimum efficiency at 50 percent of rated output. According to 80 Plus, the PSU's typical efficiency is an impressive 89.4 percent.

This power supply is not the same as the one the company includes in its M1000E blade chassis; it's a dedicated server-specific supply.

Earlier this month, Dell became the first major computer manufacturer to list an 80 Plus Silver-certified power supply for its desktops, the company reports. The 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 [PDF]] and also meets the July 2009 PC requirements of the [CSCI]," according to the company.