AX4SPE - can't get RAID to work

I have a standard AX4SPE board (not MAX or MAX II). I'm trying to get two
Maxtor 120Gb SATA drives to operate in RAID mode. However, when I set the
SATA devices to 'RAID' in the BIOS it then fails to detect the drives.

If I let it boot to the RAID utils, however, the drives show up on the list.
But again when I try to install an OS (tried Linux and Windows Server 2003)
it fails to detect the drives.

The drives are currently connected to SATA3 and 4 but I have also tried
connecting to SATA 1 and 2 with no luck. The only other drive is a DVD
writer.

I'm now at a complete loss (doesn't help that AOpen have removed the manual
for this board from their site).