LibreOffice (Xorg?) Using Wrong GPU


I think this is an incredibly basic question for someone with the right experience, but my background is more in deep learning than operating systems and the like, so I would appreciate the help. A search on the forum and elsewhere didn’t yield what I was looking for.

I have a workstation with 2xA6000s and 1xTitanXp. The A6000s are for training models and I am using the TitanXp just for video out. I updated by BIOS such that the TitanXp is the initial output display, but I encounter issues once logged in. When I open a spreadsheet in LibreOffice, a small bit of memory is used up on one of the A6000s (there are also small xorg processes constantly running on them).

So, my question is, how can I tell LibreOffice (and I think really xorg?) to not use the A6000s but only the TitanXp? I tried to fiddle around with it before and lost all video out.

I’m running Pop OS 20.04, but I don’t think that should matter here.

Any help would be appreciated!