Mac Pro does not recognize RAM

Discussion in 'Mac Pro' started by sawihsiwi, Jun 18, 2011.

  1. sawihsiwi macrumors newbie

    Joined:
    Feb 1, 2010
    #1
    Just installed two memory sticks of 4 GB each on my Mac Pro (initially 6 GB RAM). The new sticks were recognized fine but slots 3&4 (where old 1 GB sticks were) were displayed as empty - for a total of 12 GB of RAM vs intended 14.
    Restarted the computer, hoping that will solve the problem, and now slots 2, 3 & 4 show up as empty for only 11 GB of RAM.

    Hardware Overview:

    Model Name: Mac Pro
    Model Identifier: MacPro5,1
    Processor Name: Quad-Core Intel Xeon
    Processor Speed: 2.4 GHz
    Number Of Processors: 2
    Total Number Of Cores: 8
    L2 Cache (per core): 256 KB
    L3 Cache (per processor): 12 MB
    Memory: 11 GB
    Processor Interconnect Speed: 5.86 GT/s
    Boot ROM Version: MP51.007F.B03
    SMC Version (system): 1.39f11
    SMC Version (processor tray): 1.39f11
    Serial Number (system): H00360ZREUF
    Serial Number (processor tray): J503201CKBH8A
    Hardware UUID: 1EBD8D6A-075A-5D0C-B430-3766BE9566CE

    The sticks that I had used for the upgrade are:
    4GB DDR3-1066 (PC3-8500) 512x72 CL7 1.5v 240 Pin ECC DIMM

    This is running Snow Leopard 10.6.7.

    Any help will be greatly appreciated...
     
  2. drrbc macrumors newbie

    Joined:
    Oct 29, 2009
    #2
    For memory weirdness I always recommend zapping the PRAM and a SMC reset.

    The I re-read the instructions on which order and which slots from Apple.

    Then I finish seating one of the old sticks that was screwing up everything else and get mad at myself for wasting half of my day.....
     
  3. Joetazz macrumors newbie

    Joined:
    Jun 23, 2011
    #3
    Hi, I get that problem as well but I find it sorts itself out by powering down and unplugging (SMC?). Or try moving the RAM around that worked for me.
     

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