recommendation for new rig setup using Strix 1070s

Hi
Trying to setup rig the first time and hoping to get 200+MH/s, possibly from 7 GPUs.

I have 6 Asus Strix 1070s. Might get one more soon.

Looking for recommendation which Motherboard to use. Is there a mobo that supports 7 PCI-Express, any recommendation? I am assuming on a custom rig risers will be required.

Any particular riser card I should buy?

Was thinking of putting any 2 PSU, 750W each.

Processor I was thinking of going with any i3 low price one around $50 or so running Windows 10. Hoping that's good enough.

RAM I am shooting for 8GB or so.

Missing tools to build custom rig, I am thinking of ordering one from eBay where I can plug these things and also move them easily. Should I order one with extra fans, or each of these GPUs having 3 fans is good enough.

Hoping to use this rig to mine ETH, zCash or Pascal

Thanks