From TFA:

Since the noise rating equals 0 dBA at all times, you won't find any cooling fans at all in the ST30NF.

<pedant>I just have to get it off my chest as I see this mistake so often in 'silent' hardware reviews. dBA is a logarithmic scale, so 0 dBA isn't silent - that would be negative infinity dBA.</pedant>

0 dBA is extremely quiet, and fanless PSUs may be extremely quiet, but using '0 dBA' to mean 'practically silent' just perpetuates confusion over the dB scale.