We applaud the folks at Hardware Secrets for their timing. Not a week after we launched our desktop power testing, an article at Hardware Secrets pops up covering the key efficiency component we're not testing: desktop power supplies.
We probably should have clarified in our post from last week that the EnergyStar certification for computers (PDF) has two parts: system efficiency requirements, and power supply efficiency requirements. Our tests cover system efficiency, but for reasons of time and complexity we don't test the efficiency of desktop power supplies. This is why we might refer to a PC as EnergyStar compliant, but we can't confirm whether or not it's fully EnergyStar certified.
If you've heard of the 80 Plus program, you know it acts as a short cut out there to help you determine whether a power supply is efficient. 80 Plus is a three-tiered badging system that manufacturer's can stick on their power supplies and desktop specifications. At its lowest, Bronze-level rating, 80 Plus requires a power supply to use at least 80 percent of the power it draws from your wall. The Silver and Gold tiers have even more demanding requirements, going as high as 90-percent efficiency under 50-percent load for an 80 Plus gold rating.
According to 80 Plus, over 1,300 desktop power supplies currently on the market meet at least the Bronze tier, yet 80 Plus-certified power supplies are far from ubiquitous. As a rough sample, we cracked open six or seven mainstream desktops we have in the lab right now, from the likes of Asus, Dell, HP, and eMachines. Only the eMachines EL1300G-01w has an 80 Plus-certified PSU.
If you'd like to learn more about the 80 Plus certification, including the reasoning and methodology behind it, we encourage you to take a look at Hardware Secrets' article. It provides thorough, accessible background information.