Elitedesk 805 G6 SFF Add PCIE NIC no boot

[BordW]

Hello!

I bought a HPE Network card, dual SFP28 (Mellanox Connect X4) to add in a Elitedesk 805 G6. Originally the PC came with an AMD graphics card that I removed. Before doing so, I changed the VGA option to integrated in the firmware settings and confirmed I had a working screen before turning it off and add the NIC.

Once I add the NIC, the screen stays dark and the system does not boot.

I do see the NIC come alive, I get a signal over optical and I see the MAC address appear on the port on the switch. 

I turned it off, reset the CMOS with the button on the mainboard, removed the NIC and got a screen again. This time with a message that CMOS had been reset and the time / date was invalid. I configured the firmeware date/time. Add the NIC and again the screen stays dark.

What can I do? Does this card not work with an Elitedesk?

Thanks for the help!

[BordW]

its this card:

HPE Ethernet 10/25Gb 2‑port SFP28 MCX4121A‑ACUT Adapter
HPE 2-port, 10/25GbE 640SFP28 adapter
SKU # 817753-B21