Is 5gb (2x2gb+ 2x512gb) possible?

Discussion in 'Mac Pro' started by crx00, Feb 29, 2008.

  1. crx00 macrumors newbie

    Joined:
    May 6, 2005
    #1
    I have a 2.66 ghz quad core mac pro with 1 gb (2 x 512mb) ram. Thanks!
     
  2. dukebound85 macrumors P6

    dukebound85

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    Jul 17, 2005
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    #2
    as long as you have 4 ram slots which you do im pretty sure it would work. no reason not too

    make sure they are all the same speed though
     
  3. Topper macrumors 65816

    Topper

    Joined:
    Jun 17, 2007
    #3
    Yep.

    [​IMG]
     
  4. crx00 thread starter macrumors newbie

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    May 6, 2005
    #4
    thanks! off to OWC I go
     
  5. Mackilroy macrumors 68040

    Mackilroy

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    Jun 29, 2006
    #5
    When I tried that in my Mac Pro it only recognized the two 512MB modules.
     
  6. TEG macrumors 604

    TEG

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    Location:
    Langley, Washington
    #6
    Wouldn't you need to have one of each on each riser?

    TEG
     
  7. ungraphic macrumors 6502a

    ungraphic

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    Nov 15, 2007
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    Toronto, Canada
    #7
    Thats what i heard, that the ram works best when in pairs and in the same configuration on both riser cards.
     
  8. darthraige macrumors 68000

    darthraige

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    Aug 8, 2007
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    Coruscant, but Boston will do.
    #8
    And to triple confirm, my boss' MacPro (same one has you) has 5GB of ram in it.
     
  9. Inconsequential macrumors 68000

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    Sep 12, 2007
    #9
    I believe that is correct as each riser is its own channel IIRC :)
     
  10. CanadaRAM macrumors G5

    CanadaRAM

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    Oct 11, 2004
    Location:
    On the Left Coast - Victoria BC Canada
    #10
    No, RAM must go on risers in pairs -- A1 A2 have to be matching
    B1 B2 have to be matching.

    Apple delivers the new Mac Pros with 1 Gb FBDIMMs in A1 B1 but you have to move those into paird slots (1 and 2) to add any new RAM

    Pairs on a riser is mandatory -- matching 4 modules across both risers is optional, it gets a small improvement with quad-channel access.
     
  11. TEG macrumors 604

    TEG

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    Jan 21, 2002
    Location:
    Langley, Washington
    #11
    That doesn't make sense, since each riser must have the same amount of RAM, because the channel extension is done on each slot on the logic board, and therefore each riser must contain the same amount of RAM.

    TEG
     
  12. Infrared macrumors 68000

    Infrared

    Joined:
    Mar 28, 2007
    #12
    I would say so. One in the Apple shop had 5GB in it.
     
  13. CanadaRAM macrumors G5

    CanadaRAM

    Joined:
    Oct 11, 2004
    Location:
    On the Left Coast - Victoria BC Canada
    #13
    Your original premise is wrong. The risers do not have to have the same amount of RAM.

    If the A1 A2 B1 B2 pairs have the same RAM sizes, then you get 256 bit access across those slots.
     
  14. xraydoc macrumors demi-god

    xraydoc

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    Oct 9, 2005
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    #14
    Not correct. They only have to be installed in pairs. First, pair A1, then pair B1, then pair A2, then pair B2.
     
  15. Infrared macrumors 68000

    Infrared

    Joined:
    Mar 28, 2007
    #15
    So is the 2xFB-DIMM case the only one where you can have
    RAM paired across different risers?

    Except, apparently, when Apple shoves 2 1GB sticks in there :)

    Really, I would like to know why there is this special case. Thanks.
     

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