Choose what gpu dom0 should use to display gui

I have a PC with double GPU setup and I want to use monitor that is plugged into second GPU to display GUI. So far I tried to hide PCI device and looked into bios to change priority of my GPU but both failed. When I hide PCI device it just leaves me with black screen and in my bios there is no option to set priority. Before adding second GPU i had one in secondary slot and it worked but after adding new GPU to “main” slot it just want to use it instead of the original one and this outcome is undesired.

In my case without gpu priority in bios - main gpu was in upper slot (x16) or which has display cabel plugged. Switching slots for gpu’s looks like most easy workthrought

Is there no way to change it in software? I prefer to leave them in this configuration and I use display cable for both. To be honest this thing being fully automatic sounds like a bad design and one would suspect there is different way.

In software guess no, if your bios haven’t this option. Maybe its possible to customize it, but sounds for me like good way for break system, if you don’t know what to do.
I used sometime way, when i unpluged gpu in slot 1 before system start and pluged it later, but it was annoying to repeat it every time and also bug in qubes i guess, when plugged display have some visual bug, like blinking or very slow refresh rate, dunno how to describe.