Lastly the noise levels. We measured the amount of noise produced at a distance of 10 cm with three different loads, about 100W, 300W and 500W. 30 dB(A) is the lowest we are able to measure, and values in this vicinity mean that a PSU is inaudibly silent. Everything below 35 dB(A) is extremely silent, and above this level you will start to hear the power supply. At 40 dB(A) and higher the PSU is clearly audible.
The Seasonic SS-300SFD is the only completely quiet PSU here. Unfortunately, it is precisely the Gold power supply that's not so quiet.