New
#21
Use this handy calculator and add everything thing up, add all the fan slots up even if not being used you may later for heat? Then take what it gives and add at least 15%-25% as a PSU will degrade about 1.5-2.5% a year. For me I want extra headroom on any power supply so I recommend 650-850w and if you want later to OC and add more GPU's then start at 850-1200.
http://extreme.outervision.com/psucalculatorlite.jsp