Discussion in 'Mac Pro' started by Paradiseapple, Dec 4, 2012.

  1. macrumors member

    Aug 18, 2010
    Hello friends,
    I tried to upgrade my 12-core 2.66 Mac Pro mid 2010 from 4x8GB Ram=32Gb to 48Gb but the two 8Gb RAM are not recognized by the system. I have First Choice modules from late 2010 and added 2x8 Gb First Choice from this dear. In this case the Mac didn´t even start; i the second attempt I tried out 2x8Gb Samsung and the computer started but the new RaAM was not even recognized. When I tried to start the Computer with the new RAM allone - without my old RAM - it didn´t start up at all (there was just a red light for about a second on the RAM) - and: weird enough: when I reinstalled my 4x8 GB of old RAM the system asked me to put the RAM-modules to position 1, 2 and 6 and 7 instead of 1,2 and 5 and 6. The old RAM works all all slots the new RAM not in one of them.

    Who can help me?

    I´m in despair cause I need more RAM.

    Thanks for you help

  2. macrumors G5


    Oct 11, 2004
    On the Left Coast - Victoria BC Canada
    The only people who can help you are the ones who sold you the memory. First of all, these Samsung modules may be defective. The seller should replace them. Also, you need to make sure you have the correct specification of RAM. Is this seller offering modules spefically compatible with the MacPro, or are you choosing generic modules by spec? You need to also make sure you are not trying to mix ECC Unbuffered and ECC Registered modules. They can't go in the same machine.

    There is another consideration: In the case of 8 GB DDR3-1333 ECC DIMMs, you often need to match the manufacturer of the chipset to assure compatibility. So if you mix a Micron chip module with a Hynix chip module, even if it is from the same seller, they can fail to work. Contact the seller and give them all the info you can of the original modules.
  3. macrumors 65816


    Nov 15, 2010
    Edinburgh, UK
    I assume all your RAM is ECC? The reason I ask is that you can't mix non-ECC with ECC in the Mac Pro.
  4. Paradiseapple, Dec 4, 2012
    Last edited: Dec 4, 2012

    thread starter macrumors member

    Aug 18, 2010
    Thanks a lot for your replies. Yes both kinds of RAM are ECC.
    I will send the data of my present RAM to the seller of the RAM if they match.
    The strange thing is that both new kinds of RAM are not recognized by my computer. But with the old ones everything goes well.
    I only recognized that every time I restart the computer now the system tells me that my RAM is the right configuration - even when I didn´t change anything.

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