Optiplex 5050 with additional Nvidia NVS 310 - only one DP port working

Hello from Germany!

My Optiplex:

- i5, 16 GB RAM and 256 GB SSD, W10 pro 22H2, latest BIOS and all drivers are up to date

today I added a Nvidia NVS 310 low profil card to the 5050 and install the latest driver from the nvidia site.

Device manager reports the internal Intel graphic card and the NVS 310 as good, up and working.

When connecting 2 DP cables to the NVS 310, only one DELL U2415b will show the desktop.

Switching the cables just make the other U2415b showing the desktop. NVidia System Config tool reports only a single screen.

Both DP ports on the NVS 310 are working well. I install the card to an Optiplex 790 and both U2415b are working.

The device manager at the 790 only shows the NVS and the internal Intel Graphics card is not listed. Seems like the internal card is deactivated by BIOS when another graphic card is installed.

I am aware how to setup two or more screens using the nvidia system config tool.

So, my question is: do I need to deactivate manually the internal Intel card or do I have to use one DP port from the NVS and the DP port from the Intel card to get the dual screen setup working?

I cant use the HDMI port from the internal card with an HDMI-DP adapter. The KVM switch needs two native DP ports.

Any suggestions or hints in this case?

Best regards

Peter