Original Configuration - Boot from SSD plugged into SATA. Optane Disabled, CSM Enabled
Desired Configuration - Dual NVMe in RAID0 configured directly from MaximusIX Bios configuration to become the new boot drive.
PROBLEM: After reconfiguring BIOS to Intel Optane and enabling NVMe Slot 1/2 as active, disabling CSM Compatibility, which it says is required to RAID0 both NVME slots as bootable, it disables access to the original SATA to boot, so i can initiate a drive clone from my current boot partition to the new NVMe RAID. Disabling Intel Optane to gain access to SATA drive for boot access, removes access to the RAID0.
*How do i keep RAID0 as an accessible drive WHILE being able to boot from the SATA SSD, so i can clone over my primary partition from the SATA SSD to the new RAID0 NVMe m.2 pair. *
*SIDENOTE: In the back and forth, the original SSD, though no data has been lost, it is no longer bootable. DISM Repair is required to reassign it as a bootdrive so i can boot and do a drive clone. Original partition still exists and is accessible from Windows 10 File Explorer. *Just need to repair the MBR assignment in the BIOS so i can boot from it again.*
Surrealxsurvivor wrote: Original Configuration - Boot from SSD plugged into SATA. Optane Disabled, CSM Enabled
*Just need to repair the MBR assignment in the BIOS so i can boot from it again.*
I could be wrong, but it sounds like you possibly installed the OS originally in legacy BIOS+MBR boot mode, rather than modern UEFI+GPT mode. That would be confirmed if the disk is MBR partitioned rather than GPT and doesn't have an EFI partition. Unfortunately, that means that CSM is required to use the old style of boot sequence.
Here is an Intel document which may help you. It's in the context of Optane support, and they address the causes and how to convert to UEFI+GPT.