I've ordered components for my first mining rig and may have a problem with the power requirements.

MOBO - ASUS Prime Z270-A  (7 PCI-e slots, 2 M.2 slots)
GPU's - 8 x ZOTAC GEFORCE GTX 1070 TI AMP
8 x Pci-e risers
120GB SSD

PSU's - 2 x EVGA GQ 750w Gold

Where I think I might have screwed up is these GPU's require 2 x 8 pin plugs each

This is what's available on each PSU:



Is it OK to use "Y" splitters for the two 8 pin plugs on the GPU's?

I've never used risers before and they are powered, how will I power these?