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2GB DIMM on early 2008 MacPro not recognised in Mountain Lion

297 Views 9 Replies Latest reply: Nov 15, 2012 6:04 AM by Grant Bennet-Alder RSS
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Aug 5, 2012 4:30 AM



I have an early 2008 MacPro with 8GB memory fitted in 4X1GB modules and 2X2GB modules.  I have one pair installed on lower card, and 2 pairs on upper card as recommended.  After installing Mountain Lion, I find the 2GB DIMMs (Kingston) are no recognised under mountain lion.  I changed around the position of the pairs and reseated the memory but this did not make any difference


Does anyone have any ideas?



MacPro 2.8 GHZ Quad (early 2008), Mac OS X (10.5.7)
  • Grant Bennet-Alder Level 8 Level 8 (48,110 points)

    Kingston RAM comes with a "money back if not satisfied" warranty.


    If it is not working, that sounds like "not satisfied" to me.

    Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers
  • Grant Bennet-Alder Level 8 Level 8 (48,110 points)

    FBDIMMs that are no longer recognized have usually failed.


    The solution is the same, take it up with Kingston (return the pair) and they should send you ones that work under their "lifetime warranty" provisions.

    Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers
  • The hatter Level 9 Level 9 (58,560 points)

    Oh well, every new OS pushes and uses RAM more so that can be why, applications really do change and affect DIMMs as well. iTunes at one time was the "best" memory test there was at the time.


    But - they were / are marginal and that is all that matters.


    You can help by keeping the fans to 900 rpm and the temp below 70ºC

  • HumanFactored Calculating status...

    I'm having the same problem with my 2.8 8-Core Pro with 10.8.2 installed.  My OWC 2GB's read as 2GB, but my Crucial 2GB's now only read as 1GB after upgrade to Mountain Lion.  No solution here :-/  (note: My Mac is way more snappy with the bad-registering Crucial RAM installed, so I'm rolling with it.)


    On a side note, another whack problem I had after upgrading to Mountain Lion.  I had upgraded to an ATI 1024 MB Video Card while on Snow Leopard and everything was very stable.  After upgrading to 10.8 my system would Panic when shutting-down, wouldn't shut-down and would restart warning of having to restart due to a system error.  Then the Mac alerted me that the hard drive was un-repairable and to backup asap.  I tried unsucessfully to repair disc multiple times, including from a 10.8 restore partition on another disk.  I installed new hard drive and problem persisted with hard drive failure warnings.  After some "trial and error" trouble shooting, it seemed the problem went away after removing the mini display-port to HDMI adapter from the 1024 MB video card.  I removed ATI 1024 MB video card and re-installed original 512 MB video card, and now have it running with the same configuration (Cinema Display connected DVI and Samsung Monitor connected with mini display-port to HDMI adapter.  Now all systems and hard drives happy including original drive that reported problem.  What can you do??? (note: I tried three different make mini display-port to HDMI adapters before giving-up and re-installing old 512 video card.)

  • Grant Bennet-Alder Level 8 Level 8 (48,110 points)



    A DIMM that reports as half its nominal size has failed. It should be returned to the Vendor for replacement. Crucial offers lifetime warranty -- this should not be tolerated, send it back for a new one.




    ATI/AMD  cards generally require adapters that are ACTIVE, POWERED adapters. If the adapter you are using does not advertise itself as an ACTIVE, POWERED adapter, it is not surprising it does not work.


    AMD Eyefinity Validated Dongles




    A kernel panic is not ONE problem, it is one of Hundreds of problems. Kernel Panic logs are saved for later study. If you would like help with kernel panics, dig out a panic log and post it here or on a new thread.


    Mac OS X: How to log a kernel panic

    Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers
  • HumanFactored Level 1 Level 1 (0 points)

    I appreciate the feedback Grant, but unfortunately my problems are related to the upgrade.  I have 4 2GB Crucial DIMMs installed and all four started registering as 1GB after 10.8 upgrade.  Also, the video card was working fine in this system running 10.6 and 10.7.  Problems started after 10.8 upgrade.  Both the problems with RAM and video card conflict began immediately after upgrade to 10.8.2.

  • Grant Bennet-Alder Level 8 Level 8 (48,110 points)

    It is not uncommon for the changes in Operating System operation from a major upgrade to show defects in Hardware that seemed to be working fine in previous versions. new ways of working put new stresses on things, and some show their shortcomings.


    In most cases, the Operating System is not going to be changed to reach back and make allowances for your marginal Hardware. So if you are waiting for a future update to allow your marginal stuff to start working the way it used to, you are waiting in vain.


    I do not speak for Apple computer. I speak as an experienced user. I have been through quite a few major upgrades, and have never seen companies make compromises for marginal Hardware that shows its defect in a Major Upgrade.

    Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers


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