Where have my RAM modules gone ?

Discussion in 'Mac Pro' started by Rootarty, Jan 27, 2015.

  1. Rootarty macrumors member

    Nov 13, 2014
    Oh my God ! I don't need this...!

    Hi everyone,
    I put new 48GB (16BG x 4 sticks)RAM from OWC into my mid2010 MacPro (5,1). One stick in each of the 4 slots. This is the unofficial max RAM installable in this model of MacPro.

    I thought (though am not now 100% sure I checked that I checked everything was ok with all RAM modules detected after I installed the RAM several months ago) that the RAM was all properly detected by the system and everything was ok.

    Just now I noticed that when I go to About this Mac > More Info > System Report under Memory, it says that DIMM 1, 3 and 4 are empty. Only DIMM 2 is listed as having a 16GB stick of RAM (DDR3 ECC). See the image below :

    So I assume the mac isn’t recognising the other 3 RAM modules for some reason…suddenly?
    Any idea why this might be and how to fix it?
    I recently successfully installed and am using a NON-EFI (Windows) Nvidia Quadro 4000. Could this have anything to do with this issue?

    Please help.

  2. h9826790 macrumors G5


    Apr 3, 2014
    Hong Kong
    1) Do you mean 64G RAM? 16x4=64, not 48.

    2) Which CPU you are using? The 5,1 can run 64G RAM, but not all CPU support that.

    3) Did you already try some simple fix? e.g. reseat the RAM?
  3. Rootarty thread starter macrumors member

    Nov 13, 2014
    Sorry, it's actually 3 modules x 16GB making it the unoffical max of 48BG of RAM.

    I have been oping the RAM in and out of the RAM slots...and it didn't seem to be working but this last time on restarting the machine 2 of the 16GB modules are showing out of the 3 installed. It may well be the whole problem is coming from this physical non-tech problem. I'll keep at it and see what I can do. Thanks for your reply. Much appreciated.


  4. h9826790 macrumors G5


    Apr 3, 2014
    Hong Kong
    48G RAM is not a problem at all.

    I only have the 840 Evo, and it works both in the optical bay or on the PCIe card very well.
  5. thefredelement macrumors 65816


    Apr 10, 2012
    New York
    Maybe try resetting the PRAM as well.

    Also, can you swap them around and find out if all sticks work in the slots that do show up as occupied?

  6. crjackson2134 macrumors 601


    Mar 6, 2013
    Charlotte, NC
    Try installing only 1 stick at a time in DIMM slot 1 and booting. You can test each stick that way to see if one of them is defective.
  7. Dc2006ster, Jan 28, 2015
    Last edited: Jan 28, 2015

    Dc2006ster macrumors regular

    Jun 9, 2011
    Alberta, Canada
    This happened to me with RAM from Trans Intl. Once I had established that RAM stick was the problem, I contacted them by email and they sent me a new stick.

    OWC should fo the same. Contact them.
  8. Machines macrumors 6502


    Jan 23, 2015
    Fox River Valley , Illinois
    What are the makes and models of your memory modules ?

    I've had some problems with brand new modules from cheap generic eBay companies , Nemix , some OWC and the value line from TransIntl . Nemix in particular a lot of my clients had problems with and for a while was the number one reason dead Mac Pros were brought into my shop .

    I've had excellent results from used enterprise grade modules from Samsung , Micron , Hynix and Nanya . I re-certify these modules , stick them in systems and no one ever complains . Unless they add cheap stuff later to the mix .

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7 January 27, 2015