I have a Mac Pro 1st gen and I recently added three new hard drives. Bays 2 and 3 work fine...bay 4 does not show up in disk utility or system profiler. I moved the hard drive to bay 3 and it worked fine. I formatted the disk and moved it back to bay 4. Again, the drive cannot be found. Called Apple Support and they had me reset the pram and reset the system management. Still can't find it. Does the logic board handle the drives separately or as one? Could this be a cable problem or more likely a defective logic board? I would hate to spend $600-$800 dollars for a logic board just to get a $100 drive to be seen. I'm looking for suggestions as to what to do. The nearest apple computer repair is 2 hours away and they want $85 just to look at it. HELP !!