Quiet - Peaceful - Silent... Serenity. The Puget Systems Serenity Mini is as quiet as computers can get without going completely fanless, which would drastically limit the hardware that could be used. Intel's high-efficiency Kaby Lake processors are the platform for this line, and we use the compact Silverstone SG10 chassis to minimize space while still allowing flexible hardware choices internally. The stock cooling fans in that case are replaced with super-quiet Noctua fans, and the layout of those fans is adjusted to cool the components selected with as little excess noise as possible. Opting for parts which generate additional noise, like hard drives and fan-cooled video cards, can make the system more audible - but you can also avoid that by using solid-state drives (SSDs) and onboard Intel graphics.
If you want great performance with as little noise as possible, all in a small tower size, look no further.