I've been running your X5DA8 motherboard for almost six months now. Today I tried to add a 3Ware SATA controller into the motherboard. The onboard SCSI controller's firmware banner no longer shows up on the POST screen and I can't boot from it. Can you tell me how to fix this?
It sounds like your system expansion ROM is used up. If you only need to boot from the onboard SCSI controller, you can go inside the BIOS and under "Advanced" tab, PCI/PnP Configuration - disable the PCI ROM scan for that slot where the 3Ware card is plug in. Once you boot into the OS, the driver will enable the 3Ware card.