Mac Pro does not recognize RAM

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

  1. sawihsiwi macrumors newbie

    Feb 1, 2010
    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

    Oct 29, 2009
    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

    Jun 23, 2011
    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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