I'm assuming you have the x99 deluxe asus board. Is that correct? I had a problem with raid at the start, until I did a hard reset of the bios with the clear cmos button on the motherboard. then I selected raid mode in the bios under the advanced pch storage options. once I had raid mode I restarted the computer and got the raid controller to load first and saw all my drives load prior to bios loading and was able to hit "control - I" and set up my raid. Prior to hitting clear cmos I was only able to set up a software raid.
You must be careful to back up your data and not be selecting or de-selecting hard drives for raid that have unbacked up data on them, b/c the moment you create a raid volume or break a volume all the data on those disks is lost. which means if you have boot drive installed you may have to totally reinstall operating system. also once you put the bios in raid mode even if you have a drive that has your OS on it that was installed prior to selecting raid mode you will have to re-install that operating system again under raid mode. SO BE careful please! and don't blame me if you lose it all