I’ve been upgrading a lot of computers to SSD recently, and for the best performance you want to be booting in AHCI mode.   But what if you’re cloning an existing SATA mode system and need to change?   Here’s the solution:

From an Administrator command prompt, run:

bcdedit /set {current} safeboot minimal

Reboot and change BIOS to AHCI

System will then boot into safe mode and install the necessary drivers.   From safe mode, using an Administrator prompt, run:

bcdedit /deletevalue {current} safeboot

Reboot into normal mode and you should now be using AHCI mode!