If you want to build an entirely silent PC, you have to (logically) either take out or replace everything that generates noise. Every moving part inside a PC generates noise, mainly fans and hard disk drives. A common source of noise that comes from a PC is the power supply unit. These high power devices require cooling and so there are fans installed inside them. A cheap, less efficient or extremely powerful unit is commonly cooled by a fast, noisy fan. As of late, companies try to make their units more ‘user friendly’, making them more efficient so as to require less cooling, and therefore to be as quiet as possible. Nevertheless, for something to be entirely quiet, it has to be missing any moving parts. And so some companies introduced extremely efficient, fanless power supply units which generate no noise at all, for the most demanding of users.



Link: DriverHeaven