I ran into an issue with the new system I was building that is using an eVGA X299 DARK motherboard, where to my surprise it doesn’t allow me to select the PCIe slot for “Initial Display Device” like other MSI/Gigabyte boards. Supposedly by default the motherboard picks the topmost slot in use as primary display (Radeon VII in this case), however if I mix in an older card like a Quadro K4200 or a 7970, the motherboard instead picks that card as primary display regardless of slot position!?!
Ideally the configuration I want to use is to set PCIe slot1(x16) and PCIe slot4 (x16) as the GPU pass-through devices and had hoped to use a cheap nVidia GT710 in the lowest PCIe slot6 (x8 gen2) for the Linux host. However regardless of what I try, as soon as I designate the primary card as vfio-pci I lose the display for the GT710. Even though I thought it was working as I was using a display attached to the GT710, it appears that is it only working as part of the nouveau driver allowing the primary display device to share it to the GT710. Meaning that if I try to install the nvidia specific driver or set vfio-pci on the primary card, I lose the ability to display anything to the GT710 from that point forward. Is there any way to configure it such that Linux always tries to use GT710 as the primary display device regardless of the other cards, so I can maintain the ideal airflow/PCIe x16 lanes for the pass-through GPUs?
I have tried both MINT 19.2 and the latest Manjaro to the same effect, aside from buying a different motherboard where I can configure that in the bios, is there any thing I can configure to work around this motherboard’s missing feature?