One on each ide cable. and the dvd as a slave on one cable, the cd-rw as a slave on th eother.
Also if he is using raid. Raid is only designed for hard drives so make sure only they are attached to those specific ide cables.
Try Connecting all the hard drives to the raid cables.Put one on each master.
Also why does he need 3 hdd's?
Check the bios to see if it can see all the devices attached and that the raid is configured properly.
if one hard drive connected = 1+0
if one on each ide cable hen = 1+1