Intel no longer provides interactive support for this discontinued server board. As an additional recommendation, please make sure you have quiet boot disabled in the BIOS Main tab and make sure that the settings for Mass Storage Configuration under Advanced tab, are arranged accordingly to the RAID controller you are looking to use. Ensure the drives are connected and been detected.
If the issue persists after checking these settings we strongly recommend replacing the board.
Thanks for your appreciated response.
After I resetted BIOS to "Default Settings" and restarted the system, the appropiate RAID option in BIOS appeared.