I posted this in another forum and I wanted to see if anyone has any tips on assisting with my first rig...

I'm having an issue with the same board and Geforce 1070 GTX GPU combination...I can't get any of the GPU's to show up without having them plugged directly into the board. They're not under Device Manager; rather, they're a generic System Device.

I updated the BIOS to the latest version 1.7, performed a clean installation of Windows 10 in UEFI, as well as followed the instructions above regarding 4G encoding and setting PEG0 and PEG1 to Gen1. I've also made sure that I am using HDMI and NOT the onboard Intel GPU.

After the clean install, I wanted to see if I could directly plug them in and Windows recognized two. I couldn't get past two, even with the USB-powered risers. Any assistance would be greatly appreciated! I have been scouring the net for days without any progress...

MSI Z170A
Intel i3-6100T processor @ 3.2GHz
8GB Crucial DDR4
6x PCI-E1X TO 16X USB Risers
6x EVGA Nvidia GeForce 1070 GTX FTW GPU
1500W Enermax MaxREVO PSU

I used DDU to remove the onboard Intel graphics, however, that didn't work either.