How to build the ultimate silent PC

In either case, the trouble is that, while the heatsinks can radiate away a fair amount of the temperature, you really need a fan nearby sucking it away a little more quickly. That passively cooled 3D card will be beaming its heat over the motherboard, so you'll need a fan close by to whisk it away.

It is possible to slap an almighty passive cooler onto a lower-power processor – which you could always underclock if you're trying to build a near-silent PC for media centre use only – but you'll likely only end up with your case fans spinning harder to cope with the increased overall system temperature. If you only need a PC for everyday desktop work, you could pick up an Intel Atom or Via Eden ITX board – these teeny processors barely generate any heat, so their minute cooling blocks are entirely passive. Just don't expect to be watching a cavalcade of high def video on 'em.