Hi everyone.
Had an Asus AM3 m/b fail, so invested in a MSI B450 AM4, with a Ryzen 5-2600. Everything seems OK, I can set up the RAID 1 with the original pair of 1Tb WD drives, using both the Ctl-R setup, and also the Ex-RAID in Bios Settings - Advanced.
I can install Windows OK, from an image...