NEC 1080Xd User Manual page 134

Procedure when a video card is installed:
If you disable the Option ROM of the slot where a video card is installed, the VGA
console becomes unavailable. In this case, the BIOS proceeds as follows:
In BIOS Setup, "Legacy Enabled" is displayed for the slot where the video card is
installed, and "Disabled" cannot be selected.
Under the menu of the slot, the following message is displayed.
Displayed message:
This slot cannot be turned on "disabled" because the video card is installed on it.
4-26 BIOS Setup