Don't cry -    I have eight cards running on asus z-270p. Will add the ninth card next week.

Here is the setting i use for the bios:
System Agent configuration - dmi\opi configuration - dmi max link speed - gen1
                           - peg port configuration - pciex16_1\pciex16_2 gen1, pcie spread spectrum clocking disable

PCH configuration  - pci express configuration  - pcie speed gen1

onboard device configuration   - hd audio disabled

APM configuration - restore ac power loss - last state

boot - next boot after ac power loss - fast boot enabled
     - post delay time 0 seconds
     - above 4g decoding enabled  


After setting the bios, you can DDU (device driver uninstaller ) google and download it to uninstall the nvida drivers. Then you plus in the card one by one, each new card should get recognized by win 10 as basic display adapter with and exclamation in the device manager (be sure to update to latest win 10). You need to add one card, then shutdown, then add another one, then start to check again, then add one more, like this.
If any card fails to show up in device manager, may be the power supply to the card, or the pcie raiser or the card itself is bad.
- i had one bad card for which the fan is always rotating. When card recognized by OS, the fan should not assuming the mining software is not running yet.
- it can be a bad pcie power supply or riser as well
- i connect the sata SSD on sata port 3, the manual shows 0 and 5 has something that i don't remember exactly
- you need to make sure you boot from uefi mode (run msinfo32)
- or bad m2 to pcie or bad m2 to pcie power

Hope this helps. let me know how it goes