I use Windows 10. OS type is set to "win8" which also works fine for Windows 10 (devilrunner, I recommend you also set this - it may enable some specific HyperV accellerations)
One small tip for when it's set up: don't ever pass through host usb ports. Only pass through entire USB controllers...
I think you're missing the hidden=1 flag, like this:
Running latest proxmox, this also circumvents HyperV detection by setting the HyperV vendor to "proxmox" (the driver checks this field with a blacklist which does not include "proxmox" or any other bogus vendors you could...
The problem I had with my 650 Ti was that it still had a BIOS-only ROM and would not work with OVMF properly.
The 750 Ti however supports UEFI.
If, on boot, your screen connected to the GPU shows a big Proxmox logo, everything should work correctly.
I hope this is not getting annoying for everyone here, but I'm also having issues with GPU Passthrough.
First off, what I'm running:
Asus 650 Ti
Windows 10 Enterprise 1607
Nvidia Driver 372.54