Thanks for that Dinos.
Dunno wth just happened, but I connected a 2TB hard drive from my old PC to the new rig so I could copy over all my old data, rebooted, and...DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER!
Both the C300s and my optical drives don't get detected by the "IDE search" before POST, but they are detected by the RAID utility and the array is fine. The pre-POST (!) search only detects my other two SATA drives connected to the SATA 2 port.
I've checked in the BIOS that XHD is on, RAID 0 is on, boot device priority is correct, just looks as though my OS has got fried somehow. Any ideas? :confused: