PC upgrade -new MB & PSU

[Amraam]

Thanks to premiere of gtx 1080 Ti im planning to upgrade my PC to second (and some time later third) card.
Current setting:

  i5-4690k
  MB - z97 - Mini itx (one pcie 3.0 x16)
  16gb ram
  GTX 1080 FE
  PSU – 650W gold

As you can see this is not, in any case, good machine for HC  but – 1080FE is 1080FE J.
Since it is 1150 socket I can't see a point to upgrade to z270. Upgrade to X99 would best choice but it is far more expensive.   
Here is what I come up with:

  i5-4690k
  MB – ASrock Z97 extreme 4 (3 slots pcie)  (x8/x4/x4) http://www.asrock.com/mb/Intel/Z97%20Ext...dex.pl.asp
  16GB ram
  GTX 1080 FE and GTX 1080 Ti FE
  PSU – Seasonic PRIME Platinum 1200W (SSR-1200PD)

Here comes questions:
1.      PSU - will it be enough for 3 cards  1x GTX 1080 + 2x 1080 TI (TDP apx 1000W)? Any other/better options?
2.      What do you thing about MB? This ASrock is the best one I find.

Thank you in advance for any response.

[cpu_pirate]

I have had good luck with ASrock in the past, I dont think you will have any problem there.

As for the PSU, I am comparing to Titan XP since that is the closest card to the 1080Ti right now which seems to use ~300w full tilt, and typically hashcat doesnt draw the power that benchmarks do from my GPU I think you will be plenty safe with a 1200w psu, maybe even a highly rated 1000w.

[kamsulla]

checkout; https://www.amazon.com/Mining-Frame-Comp...01EGREBKM/

[Flomac]

The mobo is fine. Make sure to put the 1080 between the two Ti in the second/middle slot, since it needs the least cooling. And get a few extra fans if you already haven't

With the PSU don't go under 1200W, cause even if it might work fine, it's not very wise to run a PSU at some limit. Efficiency drops too. My rule is: system wattage x 1.5 and you're good to go. That system will draw 800W under full load so a 1200W PSU is fine.
There is a slightly older Seasonic Platinum PSU with 1200W, that seems to be a bit larger but then also cheaper. Should be fine too.

... and typically hashcat doesnt draw the power that benchmarks do from my GPU I think you will be plenty safe with a 1200w psu, maybe even a highly rated 1000w.

That's correct if you meant Hashcat uses THE MOST power any benchmark could draw
NVidia GPUs usually hit their powerlimit under Hashcat cause it typically uses all shaders all the time at full blast.