Question regarding early 2009 8x core RAM upgrade

Discussion in 'Mac Pro' started by The Mad Hatter, Feb 23, 2012.

  1. The Mad Hatter macrumors 6502a

    The Mad Hatter

    Oct 12, 2004
    Like the title says, I have an Early 2009 Mac Pro w/8x 2.26 Xeon cores.

    I want to upgrade the RAM to 12GBs (it currently has the stock 6GBs (6x 1GB)).

    If I remember correctly, it is better to add these in sets of 3. So if I get a Crucial 12GB kit (3x 4GB), do I split them up, or put all 3 on the same quad processor (essentially giving me 15GBs if I leave both slot 4s empty)?

    I would love to replace all 6 with 4GB chips but that isn't in the cards right now.

    So any advice would be helpful.
  2. Butler Trumpet macrumors 6502

    Butler Trumpet

    May 26, 2004
    Dekalb IL
    For best performance, Apple recommends you install equal-size DIMMs (all 1, 2, or 4 GB) filling the slots in the order listed here:

    If you have: Two DIMMs - fill 1 and 2
    If you have: Three DIMMs - fill 1, 2, and 3
    If you have: Four DIMMs fill - 1, 2, and 5, 6
    If you have: Six DIMMs fill - 1, 2, 3 and 5, 6, 7
    If you have: Eight DIMMs fill - 1, 2, 3, 4 and 5, 6, 7, 8

    Hope this helps!


    Also, if you install the RAM and the MacPro realizes that it is not installed optimally, a program called Memory Slot Utility will open and walk you through getting them installed in a more optimal way.


    One more thing...

    If you want to check out Memory Slot Utility manually, you can open it here: /System/Library/Core Services (just don't mess with much else in that folder)

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