sufficient power supply for evga gtx 1080 ftw acx 3.0 sli?

[123fakest]

Hey, I want to know would an evga g2 gold 850 watt power supply be sufficient for running evga gtx 1080 ftw acx 3.0 in sli? I have no plans to overclock, though I know that some cards come at higher then default clock speeds, and these cards are listed on evga's website to be larger power draws... I currently I have two 970 running in sli.

Other components include:
OS: Windows 10 64 bit
Asrock x99 extreme 4 motherboard
crucial ballistk (4x4) 16 gb ram 2400 mhz
samsung evo 850 250 gb
western digital black 1 tb hdd
intel i7-5820k processor

 

[Chugalug_]

It'll be more than enough for an overclocked 5820k, and overclocked 1080s in SLI!
You'll be perfectly fine.
If you're investing so much into graphics cards, I suggest holding out a bit longer for 1080tis, as they will likely cost the same as 1080s currently and perform/scale much better than 1080s.