said by bbear2:Thanks for confirming and the additional boot reminders. But why is it under the RAID category? This seems to imply if you're not using RAID, then you don't get the AHCI choice.
Because the motherboard (thus BIOS) manufacturer chose to put it there. The more blunt/crass version: some Chinese guy in Taiwan decided it should go under the RAID category, rather than classifying it as "SATA Mode" like it should be. Seriously, that really is the only answer.
Both modes -- RAID and AHCI -- use an option ROM, but the behaviour of the option ROM is very, very different depending on which mode you pick. RAID mode uses AHCI, but AHCI does not use RAID.
Nothing I can do about motherboard/BIOS manufacturers choosing to name/classify their stuff stupidly. You'll just have to trust me.