Step 3: Swap power supply units

The oft-forgotten power supply unit (PSU; see picture 1) is a major contributor to PC noise. Most have one or even two fans whirring constantly inside them. The more powerful the PSU, the more cooling it requires, and the more noise it generates. Applying sound-deadening material or removing the fans is a potential fire hazard, but you can buy PSUs that are specially designed to run quietly.

In pictures 2 and 3 we show how we swapped the ageing PSU from our PC with a Nesteq Semi-Fanless ASM PSU (£139 from Quiet PC). The words 'semi' and 'fanless' seem incompatible, but it provides a whopping 620W of power, and its cooling fan only spins very occasionally -- once every minute or so for about ten seconds. This makes it quieter than a Carmelite monastery. You can adjust the fan's spin speed (via the knob on the rear) for even more tranquility.

Finally, you should replace the exhaust fan from your case with quieter alternatives. In pictures 4 and 5 we show how we replaced a standard 120mm fan from our existing Antec P150B case with an Acousti AcoustiFan: DustPROOF 120mm fan (£19 from Quiet PC), which runs more quietly and provides the same level of ventilation.