100% this. I have a system with a fanless PSU from Seasonic, 3 Noctua case fans and a Noctua CPU heatsink/CPU fan. I couldn't be happier with it. It is complete

100% this. I have a system with a fanless PSU from Seasonic, 3 Noctua case fans and a Noctua CPU heatsink/CPU fan. I couldn't be happier with it. It is completely drowned out by any background noise (for example, the sound of typing, the hum of the AC, etc) and gives off a very, very faint whooshing sound when the house is truly silent. Personally I like the sound, it's the sound of high-end Austrian engineering working perfectly. I highly recommend Noctua fans.