Let's go straight-forward to the solution:
1. Power off the computer and make your SATA bootable drive to be connected to SATA's second column upper port (from left to right)
2. Install an empty NVMe drive in the M.2 slot on the motherboard
3. Start the PC and clone your bootable SATA non-RAID drive to the NVMe with Macrium Reflect
4. Shutdown the PC and remove the bootable non-RAID SATA drive
5. Connect your two SSDs to first two SATA ports
6. Start the PC and change drive settings in the BIOS to be [SATA mode = RAID] and [NVMe RAID = Enabled], then save and exit
7. Activate RAID configuration utility when prompted for [Ctrl + R] shortcut
8. Make new RAID1 array from both SSD. Save and exit
9. When your Windows boot, clone the NVMe to RAID1 array (your RAID drivers must be installed or you can't see the array) and shutdown the PC
10. Remove the NVMe
11. Start the PC and if everything is ok your Windows will boot normally. Test with CrystalDiskMark the array and check if the Read/Write speeds are around 1100/500 MB/s, something a lot lower should point to problems with the cables/drives or probably OS processes that bottleneck drive I/O
12. Profit
---
USB3 fanboys: No, it's not wise to try to clone OS from USB3 connected drive because INACCESSIBLE_BOOT_DEVICE blue screen error can pop-up and burst your holiday bubble
---
This combat mission was created by your friend Asus (written in their manual):
