Adding RAID 0 disks to a system previously setup as AHCI

Thank you @user1686 - I figured it out.

  1. connect the new disks
  2. set motherboard to RAID in bios
  3. install AMD RAID drivers and s/w in Windows (<-- had to happen after 2. above otherwise would not install correctly)
  4. setup RAID array in AMD s/w in Windows
  5. initialise and format new disks in Disk Management
  6. go to superuser and post the answer