Now that GPU's like the GTX 1080 with a TDP of 180 watts will only be designed for two way SLI and CPU's like the i7-6700k overclocked only use about 130+ watts its hard to see why you would ever need a PSU that has more than 800 watts of clean output :/ Which would still give you a 200 watt buffer with everything overclocked and running fans, drives, pump etc.
I ran a Corsair CX430 with a FX-8320 @4.5GHz with a HD 7950 @1250MHz GPU/1650MHz VRAM and two HDD's, 3x120mm fans. Its not the same CX430 you can buy now, it was a B grade high quality PSU rebadged for Corsair and used Jap capacitors. Had clean 25mw ripple at 430 watts output and could put out 460 watts within specs. I did that just to see what i could get away with lol, but it ran cool at full load and ran 24/7/365 as a gaming machine, work station, and a media/file server. But now i run a PC Power & Cooling Silencer MK III 850 that i picked up for $80 because OCZ bought them out and they dropped the price on the "PC Power & Cooling" brand. It was also open box, but a 7 year warranty covered by OCZ is fine with me.