The system BIOS allocates 128 Kbytes of address space for Option ROMs. This address space is shared between on-board devices and PCIe2 plug-in cards. This fixed address space limitation is imposed by the PC architecture and not by the BIOS itself. It is possible to exhaust the available address space when installing PCIe2 plug-in cards. When the address space is exhausted, the BIOS displays an Option ROM Space Exhausted message, which means that one or more devices cannot load Option ROMs.
By default, all on-board Options ROMs are enabled in the BIOS. However, you can disable most of these Option ROMs, unless they are required to support booting from the associated device or to provide some other boot time function (such as a video controller or the hardware RAID supported through the SAS controller HBA installed in PCIe2 slot 3). For example, it is not necessary to load the Option ROM for the on-board network ports unless you mean to boot from one or more network ports (even then, you can disable the Options ROMs for the remaining ports).
To enable or disable Option ROMs, see Enable or Disable Option ROM Settings.
For example, if you install a SCSI PCIe2 card and you encounter the Option ROM Space Exhausted message, you can either:
Disable the Option ROM for the PCIe2 slot you installed the SCSI card in if you will not be booting from that device.
Disable one or more Option ROMs for on-board devices (or slots populated with other plug-in cards) to ensure there is room to boot from the desired device.