Primary GPU Passthrough Problems

Hi,

I've been using unraid for a while now and the helped provide on the forums is fantastic.  Though my latest issue I'm a bit more stuck with.  First I should probably list what hardware I am dealing with:

Motherboard: ASUS PRIME X470-PRO

CPU: AMD Ryzen 2700X

Graphics Card 1: Nvidia 8600GT

Graphics Card 2: GTX 1050Ti

Graphics Card 3: GTX 1060

Cache Drive: Samsung 970 NVME

Other PCIe devices: USB 3.0 Card

The problem occurred after a recent upgrade in hardware, I can here the alarm bells ringing now.  I originally ran with 2x GTX 1050Ti with one passed through as the primary GPU to a VM and the other assigned to another VM.  When upgrading to the GTX 1060 though, no V-BIOS from techpowerup related to the card model would work.  They all resulted in no video activity upon initialising the VM.

So, to fix this I added the 8600GT into the system and didn't pass though any GPU as a primary card.  The only problem with this now is that the motherboard doesn't allow for the primary PCIe slot to be changed, so it is fixed at the top slot.  This forces me to use the bottom two slots for the 1050Ti and the 1060, which means the graphics cards have little room between them, as the separation between the bottom two PCIe slots is narrower than the top two.  The 1060, which is in the very bottom slot to allow it more breathing room has to use a PCIe slot, which, according to Asus, is only version 2.0 and will run at x4 mode: "1 x PCIe 2.0 x16 (max at x4 mode)" - From the specification sheet: https://www.asus.com/uk/Motherboards/PRIME-X470-PRO/specifications/  

The bandwidth limitations of PCIe 2.0 x4, if I'm correct, will be at 2GB/Sec.  This doesn't sound like enough, and in Battlefield V I am seeing less framerates compared to the old GTX 1050Ti which was located in a PCIe 3.0 x8 slot.  At first I was thinking are there too many PCIe devices, but then I thought it probably wouldn't work at all if too many were installed.  I was also weary of there being a CPU bottleneck on the new GPU as the GTX 1060 is paired with a VM with 3 Cores/6 Threads of the Ryzen.  But for FPS to go down in the game I think there is another issue with the setup.

Ideally I would like to have primary GPU passthrough working again as this worked very well with the 1050Ti and allows for the other 1050Ti to be replaced in the future.

Thank you for any help that can be provided,

Luke