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I have a 1st gen Mac Pro (MacPro1,1) with 4 internal drives:

  1. Bay 1 - 500GB - OS X
  2. Bay 2 - 500GB - Windows 7
  3. Bay 3 - 1TB - Data
  4. Bay 4 - 1TB - Data

All drives are Western Digital Caviar Black, if that matters.

For a while now, bays 3 & 4 have been flaky with recognizing the drives at all within the system. 6 months ago, I had trouble getting bay 3 to work. Now, bay 4 is having the problem. I know it's not the drive because I can swap the drives & whatever's in bay 3 will work. When the system is booted, I look through /dev to see how many disks are listed, and it's only 3.

I've tried multiple things such as resetting the SMC controller & zapping the PRAM, neither of which work. Due to the randomness of the problem & the fact that 6 months ago, it was bay 3 that was having this problem, I'm starting to think it's related to the power supply or the logic board but I'm not 100% certain.

I bought this used, so I don't have the original DVD disks that came with it, so I can't run the Apple Diagnostics. I'd appreciate any ideas.

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It might be your power supply. Have it checked out. – user3463 Jan 24 '11 at 5:08

Mac's are not my specialty but I have experience working on this model and can tell you that the built in connectors can get damaged or even corroded under some circumstances. They pinout they are connected to can also work it's way loose but this is rare.

To test wether the #4 controller or pin array is damaged, try unscrewing the two screws holding the sata/power connectors on both three and four then move the pin array from bay three to bay four and test a drive in that bay.

If this test is successful mount the old bay four array in bay three and test again. if the problem now occurs in bay three chances are you simply need to replace the array. If they both start working they may simply have settled on some corrosion and the act of removing and replacing them generally scrapes the contacts clean.

If the test is unsuccessful, the controller for bay 4 may be shot and a proper diagnostic is in order. If you do find a failed controller is the issue you can always move the drive into an external chassis but you will give up some performance using the drive externally.

Hope this helps,


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