The noise levels were measured in a soundproof box at a distance of 10 cm. This was done at three different points, namely: at approximately 100W, approximately 300W and at approximately 500W. Note that the numbers should be interpreted as follows: everything under the 30 dB(A) threshold is essentially inaudible at a normal distance. Everything under 40 dB(A) is as quiet as a whisper at a normal distance. Drives that exceed the 40 dB(A) threshold are clearly audible. Technically speaking every 3 dB(A) is a doubling of the noise, but the human ear perceives every increase of 10 dB(A) as about a doubling of the noise.
The noise levels of the Seasonic Prime Gold and Platinum power supplies at low load is very low. After 5 minutes of load with respectively 100 and 300 watts all of the models are practically silent, and only after we increase the load to 500 watt for a longer period of time the fan noise becomes clearly audible. This means that the Prime power supplies do not perform bad at all, but as the graph at the bottom of this page shows, there are power supplies that are a lot quieter.