I have 4 PC's and 3 video cards, just trying to get one working with Mav and Mo.
I found to boot a non supported card you need to disable it nv_disable=1
This video is helpful
and Clover Configuration is great https://www.macupdate.com/app/mac/61090/clover-configurator
So I managed to get it...
I had a GT 610 in Mojave but it was jerky, so I put a GT 710 in and that works fine but now Mavericks on the other drive won't boot.
Tried -x but still won't boot, I booted back with the GT 610 to try and install web installer driver but I get "Computer not Supported"...