Stupid of me, found it , tech support from AsRock excellent:
From AsRock Technical Support:
Please kindly try the following steps to build UEFI RAID volume.
1. Enter BIOS > Advanced > Storage Configuration > Set [SATA mode] to [RAID mode]
> ACPI Configuration > Set [CSM] to [Disable]
2. Reboot system and enter BIOS again.
3. Enter BIOS > Advanced > Intel Rapid Storage technology will appear at the bottom.