That's the same as when installing a separate card rather then using onboard video where you then change the PCI/AGP or PCI/PCI-Express pci setting to the other one and see that the onboard is disabled. Otherwise you see nothing onscreen when starting up with the monitor plugged into the video card then installed.
On every board since onboard sound was first being seen I always disable that and use a card. The onboard then becomes a last resort if a card fails.
Gee? Still using those cards iwth the Creative Sound Blaster icon on them even for the Xtreme Gamer in use.