Mac SCSI Problem

Wondering if any of the mac user could help a friend of mine out

his set up is

Mac G4 dual 125hhz, OS 9.2.1, 2GB RAM, Pro Tools Mix ++++, ver 5.3.1csi, ATTO dual scsi card, AVID x 3 LVD 36GB drives

and the problem is

Mac won't boot when drives are switched on and ATTO Express hangs when scanning for drives.

I know nought about macs so i'm not much use to him

might be one of a few things (im no scsi expert btw)

What i would check:

Cables
SCSI I.D. numbers
Take out SCSI drives one by one
Try different SCSI card
Re-install drivers
Try different RAM.