These are the availble cables in the psu.

These are the cables in the box

1 x power 24 pin ATX with detachable 4 pin section
2 x power 8 pin EPS12V with detachable 4 pin ATX12V section
6 x 8 pin PCI Express power with detachable 2 pin section
10 x 15 pin Serial ATA power
5 x 4 PIN internal power
1 x 4 PIN mini-power connector


So from my understanding i will use

GPUS(3xgtx1070)

8 pin connector from PSU to GPU using power 8 pin EPS12V with detachable 4 pin ATX12V section
8 pin connector from PSU to GPU using power 8 pin EPS12V with detachable 4 pin ATX12V section
6 pin connector from PSU to GPU using an 8 pin PCI Express power with detachable 2 pin section
 
Risers
3 risers connected to psu using 8 pin PCI Express power with detachable 2 pin section

Thanxs for your patience