Nvidia 610 for desktop. I'm using the desktop driver from their website dated late 2017, because their website drivers dated 2018 did not install in the Optiplex 7050. The 7050 is very finicky about drivers, so maybe a newer driver would work in other hardware.
No... Just no... The machine itself doesn't care about a graphics card driver. Your issue is using a variant of the GT610 and trying to install a driver newer than 391.35(the last driver that fully supports Fermi-/Kepler-based gpus). Based on your graphics card's hardware id, a newer driver COULD refuse to install, but that's not because your graphics card is shoved inside a Dell Optiplex 7050...
Actually, I used a slightly older driver than 391.35. I had to reach back to 2017 for a driver that worked. Sorry about the confusion though. I was actually referring to none of the Dell / Intel drivers working. Therefore, the need for the Nvidia card and driver. Similarly, the Dell USB drivers did not work, so I used the generic driver linked at the beginning of the Simplix thread in here.