Hardware:
1. MSI z270 SLI Plus Motherboard
2. ( 8 ) MSI gtx 1060 6GB gaming cards
3. EVGA 1000w psu
4. 16GB corsaire 2400mhz ddr4 ram
5. i3 intel cpu
Trouble shooting:
1. updated bios to latest
2. set up windows 10 WHQL support to allow m.2 support
3. fresh install of windows in raid and uefi
4. installing each card 1 by 1 with restarts after each one
5. swapped m.2 to pcie cards for hardware failure but last slot still not working
6. enabled gen1 and 4g decoding
7. almost threw machine out window
Try setting PCEx to Gen 2. Use DDU uninstall driver in safemode. Put all 8 GPUs in, then install driver.
Don't install driver 1 by 1.