Setting up a Second Graphics Card

I have a RTX3060 which will output to 4 monitors (3 x DP, 1 x HDMI), and is not MST-hub compatible despite being DP1.4 standard. I have 5 monitors, so picked up a second graphics card, a GT 720 (2 x DP) to drive this monitor and perhaps another monitor (minimal graphics requirements on each), and installed it in a spare PCI slot on my ASUS B550E MB (I have a 1000W PS, so power is not an issue).
Having a VERY difficult time sorting out the drivers, as on boot, the system (Win 10 64 pro) recognizes the 720, but immediately disables the 3060, leaving me with 1 monitor, not the outcome I want.
What do I need to do so that I can have all 5 monitors displaying in an extended desktop mode?