Of course it is important that a power supply does its work as quietly as possible. Just as we do in all of our other sound tests we measure this in a soundproof box at a distance of 10 cm, with a noise floor of 18 dB(A). Note that the numbers should be interpreted as follows: everything under the 30 dB(A) threshold is essentially inaudible, 40 dB(A) is clearly audible and 50 dB(A) is loud.
We conduct three sound tests, with a load of a 100 watt, 300 watt and 500 watt. We conduct the first two sound measurements after 5 minutes and the third test after 20 minutes You can consider the first test an idle sound measurement, for the second test you can expect results for ‘average’ usage and the third test shows results for when the power supply is under heavy load at great length. Considering the fact that there is not much airflow, you can see the third test as a worst case scenario.
We see many power supplies in this test that cannot be assessed as inaudible, maybe because of the relatively large number of lower positioned models. Fourteen power supplies in this test produce even more than 30 dB(A) sound at 100W load. The other thirty stay below 30 dB(A). With 300W this number increases to seventeen, but still the majority of power supplies is inaudible. With the 500W stress test this is no longer the case: now 32 power supplies do not succeed in staying inaudible. The most silent power supplies are the Seasonic X-Series 650W V2, the Corsair CS650M, plus the Be quiet! Pure Power 9 CM 600W and finally the Dark Power Pro 11 650W.