My desktop is completely silent aside form a very small buzz from the GPU when I load a web page or something. It only lasts for a little less than a second. The key is that it has no moving parts. No fans and a SSD. The CPU, GPU and north bridge are water cooled. The pump and radiator are down stairs in the basement in my utility room. The radiators are a couple heater cores from Bonneville's and some giant 5' long hydronic turbulating contraption that's designed to be cast into a concrete slab. When I finally finish my basement and get the kids PC set up I'm going to move to cooling that as well as my file server with the pump and radiators. Maybe not low power but the usage for my PC is pretty close to a laptop since I don't have some giant GPU for playing video games.