Internal Graphics Mode Select is further described on page 31 - it has to be set to "AUTO" before a PCIE graphic card is detected and used. Do you have that set correctly in BIOS?

If your graphics card is not working after installing a BIOS update in Windows 11/10, here are some working solutions that will help you resolve this problem.

If you have accidentally disabled the graphics card driver on your Windows computer, your display will turn black. This article lists some fixes that will help you.