Selecting POST display GPU on a Crosshair Hero VII?

I am trying to output the bios display in the last PCIe slot on an Asus Crosshair VII Hero motherboard (the 4x slot). I need to output the display specifically from the GPU there for a VM project I am working on, and I don’t see any options to do this in the BIOS settings. When I have the three GPUs I need all slotted it will only display out of the first PCIe slot. Tried searching online but couldn’t find answers. Thanks

Maybe @wendell has a idea, I don’t know if this works with a consumer Mainboard