I was trying to set one of the pcie x16 to 4x4x4x4 to add another 4 m.2 drives using an adapter card. I know the setting should under Device Manager -> Platform Manager -> PCIe Root Complex, but I really have no clue which Root Complex is corresponding to which pcie slot on the carrier board. I changed Root Complex 0 setting, and USB ports stop working. I have to buy a D9 to USB adapter to access to the EFI again.
It would be appreciated if some help or documents can be provided.