So I ordered a Dell 3891 with Toshiba 1 TB SATA drive. I wanted to add a SSD drive, so I got a 256G M.2 drive. Copied the data from SATA drive to SSD drive. I wanted to boot to the SSD drive, so i went into the BIOS and boot options said Windows, UEFI 8X optical drive, UEFI hard drive, UEFI USB devices, Onboard NIC. I selected UEFI hard drive, and it booted from the new SSD drive. However, when I went back into the BIOS, the Windows option or to swap back to the SATA drive was not an option. Is this because RAID is on, or I can never boot from the SATA drive again without completely disabling the SSD drive?