Home theatre PC, normally a small, low power very quiet system for playing movies and listening to music. Personally I have a bluray player in my PC and couldn't really live without it. Granted most gaming rigs aren't the quietest of beasts, but with some decent fans (silent eagle 1000 for example) and good speakers, it doesn't really matter.
The HX850 is a very good PSU, couldn't praise it highly enough, the only one which can match it (not in power) is the HX750. The new Seasonic gold 80 plus PSUs are supposed to be very good, but I'd stick with the corsair.
i7 5960X 4.5GHz -EK Supreme EVO - Asus - X99-WS-E - 32GB 2400MHz RAM - Titan X EK Cu Block - Creative Titanium Pro - TJ07B-W - Plextor 240GB PCIe SSD - 3TB HD - Dual Loop