What is an 80 PLUS® Certified PSU?
80 PLUS® specifies internal form factor voltage outputs, as well as Bronze, Silver, Gold, and Platinum criteria levels for energy efficiency and power factor.
For a given power supply, efficiency varies depending on how much power is being delivered. Supplies are typically most efficient at between half and three quarters load, much less efficient at low load, and somewhat less efficient at maximum load. Older ATX power supplies were typically 60% to 75% efficient. To qualify for 80 PLUS, a power supply must achieve at least 80% efficiency at three specified loads (20%, 50% and 100% of maximum rated power). However, 80 PLUS supplies may still be less than 80% efficient at lower loads. For instance, an 80 PLUS, 520 watt supply could still be 70% or less efficient at 60 watts (a typical idle power for a desktop computer). Thus it is still important to select a supply with capacity appropriate to the device being powered.
It is easier to achieve the higher efficiency levels for higher wattage supplies, so gold and platinum supplies may be less available in consumer level supplies of reasonable capacity for typical desktop machines.
Why is it important?
During the transmission and conversion of electricity, a certain loss of power occurs. In the case of power supplies for computers and servers (and most gear, actually), the loss translates into heat, a worrisome development that requires the consumption of more power (see where we’re going?) to drive fans to push away that heat from circuitry that doesn’t take kindly to temperature extremes. The knock-on effect is that datacenters need to vent this hot air and supply cool air, resulting in more energy costs. Note that processors, RAM, drives and mother/daughterboards generate heat too, so PSUs aren’t the only culprit.
But the real problem is that a good chunk of the electricity that you spend money on never reaches your computer’s components. So, not only are you paying to generate and expel waste heat during the AC/DC conversion process, a lot of the earth’s resources are being consumed to ultimately power nothing.
Bottom line: Enjoy the benefit of a smaller energy bill, longer-lasting gear, quiet performance through reduced thermal output, and good old green IT karma.