Enable second graphics card on Debian 10.5?

There’s an onboard graphics controller on this motherboard ROMED-8T. I have to have that enabled in order to get any graphics (it doesn’t seem to work with a PCIe card as the primary). But the onboard graphics is a DB15 and I’m trying to get an HDMI output, so I’ve added a PCIe graphics card (Radion based) and it shows up in lspci (with a radeon driver), but it does not show up in the graphical “displays” tool that let’s you enable/mirror/reorder monitors. I’m also not seeing it in the xrandr providers list.

How can I go about trying to enable this card to drive a second display?

It looks like xorg.conf is gone in Debian 10.5… it’s now a directory but doesn’t have the configuration information that I’m expecting to find in it.

Are you using Wayland or xorg as the display manager. If you are using the latter then xorg is a thing but X now uses defaults probed with drm and mode setting.

But hybrid graphics are hit or miss on the *nix platform. Take look here.