Hello,

 

I have one GPU in slot 1 on mother board (asrock x370 taichi) that I pass through to the VM. 

Then, I have a second GPU in slot 2 that I want to use specifically for Unraid.

When server boots up, it always uses the first GPU until the certain point where it get's black listed.

I get no output on the second GPU. It is showing up under System Devices. I can not change this behavior in BIOS because the option is greyed out.

 

I guess my question here, is there anything I can do in the config file to dedicate second GPU to unraid? I really don't want to move second GPU to slot 1 if I don't have to.

You really need to set which slot contains the primary GPU in the BIOS. Here's what worked for me on an Asus Prime X470 Pro. Install the cheap GPU that you want for Unraid in its slot (I actually used the bottom long slot of three, which runs at a maximum of PCIe 2.0 x4, but can drop to x2 if the x1 slots are used) but leave the more capable card you want to pass through unconnected for the time being. I was then able to set the primary graphics card in the BIOS. Once I had that set I was able to install the better card in the top long slot (and, incidentally a SAS HBA in the middle long slot so they got eight lanes of PCIe v3.0 each) without it being used either by the BIOS setup or by the OS. I helps to keep a monitor connected to the lesser card while doing this.

It was worth the try. It doesn't matter what I do, slot1 is always the primary. I ended up swapping my cards around. Gonna test now and see if there is difference in performance. I believe both slots were already running in x8, so I don't think it should matter a lot.