PSU help! 850W vs 1000W

[Gnuffi]

Final call for help!
Today is confirmation day for my build order, and im stuck on what PSU i should take:
EVGA SuperNOVA 850 P2 - 850W
Corsair RM1000i Gold - 1000W

My build is:
Z170 Maximus Viii Hero
i7 6700k (will shoot for OC to 4.6GHz)
2x16Gb G.Skill RipjawsV DDR4-2800 C14 (because lol)
NH-d14 Cpu cooler 7 Noctua case fans (doubt can run them in low volt mode with OC but will see)
2x ssd and an optical drive
and sli 980ti's (or whatever Polaris/Pascal will be coming, since they will prob have lower power usage felt safest to stick with 980ti's as base)

They both have stellar reviews such and such and are for all reasons considered equal/identical
Right now i can get them at the exact same price is not an element to factor in NOR is the warranty

Do i need/benefit at all from the rm1000i's extra 150 watt? or is it pointless for my build with more than the evga 850?
(Should note reason for not going for the 1000w evga is size, corsair is slightly smaller and will fit in my build, evga 1000 will not)

So do i need the 1000w in any way? any benefit to the corsair rm1000i over the EVGA? will the EVGA 850 and its quality be enough to beat rm1000i?

PSU masters advice me! clock is ticking

 

[turkey3_scratch]

Get the RM1000i. Some headroom is always good because the PSU is not stressed as much, meaning it can last longer (though either should last very very long anyway). And I mean, for the same price, I'd just get it. You also get the Corsair Link software, if you're into that stuff. Power supplies are also more efficient near 50% of their operating load.

Your system under stress is about 700-750W. Here is efficiency for the RM1000i.

Note the 230V AC wall socket. How that would compare to the EVGA P2 is subject to debate. The EVGA very well would probably be actually more effieicny, if you're all into saving something like under $1 a year on the electricity bill.

 

[djreedj]

I actually set up 980ti sli today on my 850 evga g2 supernova and ran beautifully, thats a beautiful psu and you wont be disappointed with it. Iw ould choose evga!

 

[Gnuffi]

well, turns out the 1000w psu is 10mm too big so that pretty much takes out that option
and sadly EVGA's 1000w psu are even bigger, and the GS/PS that do fit, ofc isnt sold anywhere near here x) (sucks to not live in the US right now lol)
850 will have to do

 

[turkey3_scratch]

The 850 P2 will be perfectly fine.