Hi Kevin/Paul,
i was struggling through these newsgroups and found another similair case, and there was an option and cause i also not think about ( because another division in my division that use the same configuration, but with smaller disks dont have this problem). according to this the mainboard is faster that the spinning up of the large disks, this can give this error, he gave the tip ( for testing) to try to include a pauze in the boot process. i attach a "empty" raidmanager board ( so that the bios is also looking at this one, during this i hope the disks have more time to spin.
let you know