Hi, I saw your post. I too have a GIGABYTE 970A-D3 motherboard and having problem with making the on-board Lan controller work. Have you found a solution to make it work?
I am also having problems with the usb ports, the usb devices (keyboard, mouse, flashdrives etc) are not recognized unless they are plugged in to the blue usb v3 port. I tried with several other linux live distros and every usb ports work perfectly fine. Have you experienced something similar? Maybe I have some setting wrong in the BIOS that conflicts with Proxmox, but then again how come that other linux live distros work just fine. Thanks for your feedback.