PSU efficiency (80 PLUS)

PSU efficiency is the share of AC wall power a supply actually delivers as DC to the system, and 80 PLUS is the program that certifies it. Labs test at fixed load points, usually 20, 50, and 100 percent of rated output. Whatever does not reach the components leaves as heat. A unit earns a tier, from Bronze up through Silver, Gold, Platinum, and Titanium, by clearing the efficiency minimum at every tested load.

Gold is the tier most enterprise specs call for by default. On a 115 V unit it requires 87 percent efficiency at 20 percent load, 90 percent at 50 percent, and 87 percent at full load. Titanium adds a 10 percent load test and pushes the 50 percent figure to 94 percent. Every tier also requires a power factor of at least 0.9 at full load, which measures how cleanly the supply draws current rather than distorting it.

Efficiency peaks near half load, so size a supply to run around 50 percent at typical draw rather than close to its rated wattage. Gold is a sensible default for a single workstation. For a rack running near continuous load, Platinum or Titanium shows up in the power and cooling budget.

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Last verified August 29, 2026.