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Is 80 PLUS Broken? How To Make It A More Trustworthy Certification

5VSB Efficiency

The ATX specification also states that the 5VSB rail's efficiency should be measured as well. However 80 PLUS totally ignores it, even though we consider this rail important.

So far, we've run into a number of Gold- and Platinum-certified PSUs with low-efficiency 5VSB rails. In our opinion, an efficiency certification should take into account all rails, not just +12V, 5V, and 3.3V. As a side note, the -12V rail isn't required by the most recent ATX spec, since there aren't any PC components that use it.

We conduct four load tests on the 5VSB rail with 0.1A, 0.25A, 1A, and full load. We are thinking about adding three more measurements, with load levels of 0.045A, 0.09A, and 0.55A. These load levels are provided by the ErP Lot 3 and Lot 6 directives, which require higher than 45% efficiency for the first two and at least 55% for the last one.

5VSB Power ConsumptionSystem AC Wall Power ConsumptionEfficiency
≤0.225W< 0.5W to meet 2013 ErP Lot 6 requirement (100V~240V)>0.45%
≤0.45W< 1W to meet 2010 ErP Lot 6 requirement (100V~240V)>0.45%
≤2.75W< 5W to meet 2014 ErP Lot 3 requirement (100V~240V)>0.55%

There is lots of deviation in the efficiency readings under such low loads, so you have to use a logging program in order to take accurate readings.


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Aris Mpitziopoulos
Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.