What hardware to pair with 4x1070ti?
#1
Brick 
I'm helping put together a build that will be primarily used for hashcracking, it'll be running upwards of 75% of the time and starting with 4 gpus and planning to add another 2 over the long term. Mostly NetNTLMv2 and the occasional WPA handshake.

I've seen benchmarks, for the performance I want I'm planning:
 - 4 blower 1070ti cards
 - 8x8gb (is it worth going higher speed?)

To be decided:
 - Server case, 4U or 6U
 - Mainboard
 - CPU(s)
 - Storage (I'm assuming I can just grab a .5TB  860EVO or something?)

Help very much appreciated, I've built plenty of desktops before but never a server or dedicated cracking rig.