It took some trickery (that I don’t remember) but I was able to get my 3080 laptop to support the ancient unsupported Nvidia GPU with both running their correct drivers. Have you tried fiddling around with updating and rolling back drivers in device manager?
And unless you need the certified drivers (which it sounds like you might not even be able to use) or the extra floating point performance then quadros are a waste of money.
Also from what I can tell modern GeForce and quadros can only drive 4 displays at a time. My ATI 5870 from 2010 can do 6 displays, but for whatever reason they decided that was too many and went back.