I just bought a used MacPro3,1 on Amazon. The system came with Mac OS X 10.6 but I downloaded Yosemite and it states that one of the 2GB modules is faulty.

Faulty 2 GB Module as listed in About this Mac

When I installed Yosemite it wiped out diagnostics for Apple Hardware Test (AHT) but this isn't a big deal as it can be downloaded and booted from USB for particular Mac models. When I ran the AHT in extended testing mode (a test that runs for two hours) it states that I don't have any issues:

AHT with "no trouble found" displayed and "Pass Number 1, Total Time Testing: 2 Hours 3 Mins 18 Secs"

Module listed as having EEC Errors


The new RAM came in, and I put it in in place of the bad RAM, and the same spot is still showing the EEC errors. The replacement RAM I was sent had a different number on it then the rest of the RAM, but I'm starting to think it isn't the RAM, it's maybe the Reiser. Can anyone confirm this? Can this damage the RAM? However sometimes, it boots and doesn't have an issue with the RAM. I'm starting to think it has something to do with sleep mode.

Modules with Full RAM and same slot complaining about EEC Errors

EEC Errors

Update 2

Okay so it's definitely the Riser. I swapped Risers, and waited a little bit and now it's reporting it on the other Riser.

Switched out Riser now it's on the other side

  • Using the About This Mac, can you check if all RAM's are the same model? – Ruskes Dec 7 '14 at 16:58
  • I don't know...I could open it up to find out though, I guess. They have to have the same kind in Bank A, Bank B as such though right? – leeand00 Dec 8 '14 at 3:55
  • Actually before using a screwdriver, open about this Mac more ect.. then click on memory and compare the info for each one listed there. – Ruskes Dec 8 '14 at 4:09
  • It says something about ECC Errors: support.apple.com/kb/TA27175?viewlocale=en_US seems to mean something about impending DIMM failure. What causes this? Age? – leeand00 Dec 8 '14 at 22:37
  • 2
    It looks like it might be a paired unit. Try populating the A3 and B3 slots. – Ruskes Dec 9 '14 at 0:32

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