Pro memory config please

Discussion in 'Mac Pro' started by sspeed, Jan 2, 2010.

  1. sspeed macrumors newbie

    Joined:
    Jan 2, 2010
    Location:
    Lancashire
    #1
    Hi Everyone..
    I am new to this forum and pretty new to Macs generally.
    However I am lucky enough to own a 2009 Mac Pro which has 8GB of memory (2 x 4gb)..
    I have aquired another 8GB of memory but it is 4 x 2GB sticks.
    I hear that the Mac Pro is very particular about how memory is installed.
    Please can you advise how I install with maximum performance in mind.
    Thanks in advance for any help you can offer,

    Simon
     
  2. gugucom macrumors 68020

    gugucom

    Joined:
    May 21, 2009
    Location:
    Munich, Germany
    #2
    Best performance for a MacPro4,1 octad requires six identical DIMMs. This is because each CPU has three channels which should be filled with the same amount of compatible memory.

    Assuming that your 4 and 2 GB DIMMs are both of UDIMM type (unbuffered) you could buy two more 4 GB DIMMs. An optimal configuration would be:

    Slot Size

    1.......4
    2.......4
    3.......2
    4.......2

    5......4
    6......4
    7......2
    8......2

    In this case each channel would be filled with 4 GB because slot 2 and 4 serve the third channel and slots 7 and 8 serve the sixths channel. There may be minimal bandwidth losses compared to six identical DIMMs but it is not worth consideration under the real world conditions of your system.
     
  3. sspeed thread starter macrumors newbie

    Joined:
    Jan 2, 2010
    Location:
    Lancashire
    #3
    Thank you

    Thank you very much for such a quick response..
    I shall order 2 x 4GB sticks of memory..
    Have you any suggestions where to buy from?
    Thanks in advance
     
  4. gugucom macrumors 68020

    gugucom

    Joined:
    May 21, 2009
    Location:
    Munich, Germany
  5. sspeed thread starter macrumors newbie

    Joined:
    Jan 2, 2010
    Location:
    Lancashire
    #5
    Excellent

    Once again, thank you.
    There is indeed quite a price difference.
     

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