Mac Pro (Nehalem, 4,1) Memory Upgrade

Discussion in 'Mac Pro' started by funkahdafi, Feb 13, 2011.

  1. funkahdafi macrumors 6502

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    #1
    Hi,

    I have the Nehalem Mac Pro (I think it's 2009? MacPro4,1) with Quad-Core processors. Currently I have 6 of the 8 available memory banks deployed with a total of 12 GB Ram.

    Now I need more. But as far as I remember, the Nehalem memory architecture runs best if memory is deployed in members of three banks (like 2 * 3 * 6 GB).

    What would happen if I use the fourth banks? Would I see a performance drop?

    Thanks
     
  2. SuperJudge macrumors 6502

    SuperJudge

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  3. Hellhammer Moderator

    Hellhammer

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    #3
    More memory will nearly always yield a higher performance than dual- or triple-channeling setups would. Only very few apps can take advantage of such high memory bandwidths. Just get more memory and fill the remaining slots
     
  4. funkahdafi thread starter macrumors 6502

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    #4
    Ok, thanks.

    Say all my banks are filled with 2 GB modules. Would it be possible to put 4 GB modules in the remaining two slots?

    And while we are at it, what kind of memory do I need exactly for that model?

    Thanks!
     
  5. Hellhammer Moderator

    Hellhammer

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    #5
    Yes, you can use 4GB modules. You could check OWC, TransIntl and Crucial, they sell RAM that works in Mac Pros
     
  6. DeeEss macrumors 6502a

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    #6
    even if you follow the triple channel theory the difference in performance hit is something as little as 1 or 2%
     
  7. funkahdafi thread starter macrumors 6502

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    #7
    All right, you got me sold, I am going to upgrade.

    The question that still remains: What RAM modules exactly do I need? I know where to buy it, but I need specifications.

    Thanks again!
     
  8. Hellhammer Moderator

    Hellhammer

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    #8
    http://manuals.info.apple.com/en_US/Mac_Pro_2009_2010_Memory_DIMMs_DIY.pdf
     
  9. funkahdafi thread starter macrumors 6502

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  10. funkahdafi thread starter macrumors 6502

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    #10
    Actually I have more questions:

    As I said, I currently have 6 * 2 GB, spread across slots 1-3 of each memory riser.

    Regarding to a FAQ here on MacRumors, I should install matching PAIRS:

    "The RAM must be installed in matching pairs, in this order: Riser A slot 1&2, Riser B slot 1&2, Riser A slot 3&4, Riser B slot 3&4."

    Are you guys sure I can put 4 GB modules in the remaining slots? My understanding of this FAQ (while english not being my native tounge) is that I have to put the same size modules in slot 3&4. Since 3 is already loaded with a 2 GB module, I am kind of nervous buying 4 GB.
     
  11. funkahdafi thread starter macrumors 6502

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    #11
    forget it.. just called apple (I have apple care). regarding to the guy, my remaining slots nr. 4 and nr. 8 would form a pair, so the 4 GB modules in there should work.
     
  12. Hellhammer Moderator

    Hellhammer

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    #12
    In the past, memory had to be installed in pairs but that is not the case anymore. It will work fine. Also:

    From the link I posted above.
     

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