Dell Optiplex 790 with a single PCIe 2.0 16X slot. I have a pair of 4K monitors and need a card that will drive them (CAD applications) clean, like automagically set up on an existing Ubuntu18.10 setup (installed 18.04, it went and upgraded itself evidently). Have seen RX550 based card suggested but these look short of connectors (1 ea, HDMI, DP and DVI). Have seen assertions that HDMI and DVI will make monitors / cards downrange the resolution, while DP has Linux support problems.
Looking for “worked for me” type recommendations that fit the machine and the monitors.