About a year ago, I searched high and low for a fanless power supply above 400W which was completely silent, but was disappointed with electrical buzzing noises coming from the most recommended power supply (Seasonic X 460).

Is there a fanless power supply now that makes absolutely no buzzing noise whatsoever? Surely it cannot be so hard to make one. If high-end smartphones and ipads can be completely silent, so can computer power supplies!

Sometimes it is an interaction between major components in a system, that cause buzzing. The motherboard and the video card in particular can often do this.

It's a defect if a PSU does this. The manufacturer will claim it's within tolerance, but no PSU is designed to buzz.

It's usually power conversion circuitry that emits these noises. Mainboard or graphics cards can emit them too, so can monitors.

Smartphones and tablets run off batteries and don't need to convert 120/230v down. But their chargers do and I've encountered at least one smartphone charger that buzzed/whined.

To sum it up: Buzzing PSUs are like monitors with dead pixels. You shouldn't get one, but you sometimes do. Shop online and return the defective item if necessary.

PSUs have some pretty large currents flowing inside them, which mobile devices don't. While I'm sure manufacturers could do better, it is an inherently difficult problem to solve.

My fanless PSU does not make any electrical noise that I can hear (however, the review on this site claims "you can hear the trace of buzzing and whine common to all power electronic circuits" so if that's true I don't think any PSU will ever be truly silent). While they don't make it anymore, the new 400W PSU from Silverstone looks to have a similar build quality:

http://www.silverstonetek.com/product.p ... 28&area=en

Good Luck