Switch the Option ROM back on, and backup any important data. Create a bootable Linux live CD or USB, and create a Windows 10 (assuming you're running Win 10) install USB.
https://help.ubuntu.com/community/LiveCD
https://www.windowscentral.com/how-create-windows-10-usb-bootable-media-uefi-support
Switch the Option ROM off and boot off the Live CD. Confirm that the Windows disk is readable and the partitions are still there (you should be able to browse the files). If the partitions are not visible, then RAID mode configured the drive differently than AHCI mode, and your only recourse will be to reinstall. (If you have a large external drive, you might be able to backup the partitions with the Option ROM enabled, disable it, then restore those partitions using a program like Easeus Backup.)
If the partitions are still there, boot off the Windows install USB. Perform an automatic repair. From what I've seen of motherboard RAID chipsets, this is the most likely scenario.
https://www.boyans.net/RepairWindows/repair-windows-boot.html
If that doesn't fix it, you can try a manual repair.
https://www.lifewire.com/how-to-rebuild-the-bcd-in-windows-2624508