MacPro : memory population problem

Discussion in 'Mac Pro' started by UltraNEO*, Aug 14, 2008.

  1. UltraNEO* macrumors 601

    UltraNEO*

    Joined:
    Jun 16, 2007
    Location:
    近畿日本
    #1
    Hiya there, a question for those power users....

    Today I attempted to upgrade my MacPro from the default 2Gb of Ram with an additional 8Gb of ram. The New modules have been added to banks 2 and 3, the original memory is still in bank1. However the system refuse to see all! Instead i get the following....

    Set A
    Dimm 1 : 1Gb (original)
    Dimm 2 : 2Gb (new)
    Dimm 3 : 2Gb (new)
    Dimm 4 : 0Gb (empty)

    Set B
    Dimm 1 : 1Gb (original)
    Dimm 2 : 2Gb (new)
    Dimm 3 : 2Gb (new)
    Dimm 4 : 0Gb (empty)

    Total shown is 6Gb RAM

    After a reshuffle....

    Set A
    Dimm 1 : 2Gb (new)
    Dimm 2 : 2Gb (new)
    Dimm 3 : 1Gb (original)
    Dimm 4 : 0Gb (empty)

    Set B
    Dimm 1 : 2Gb (new)
    Dimm 2 : 2Gb (new)
    Dimm 3 : 1Gb (original)
    Dimm 4 : 0Gb (empty)

    Total shown is 8Gb RAM

    Another tweak...

    Set A
    Dimm 1 : 2Gb (new)
    Dimm 2 : 2Gb (new)
    Dimm 3 : 0Gb (empty)
    Dimm 4 : 1Gb (original)

    Set B
    Dimm 1 : 2Gb (new)
    Dimm 2 : 2Gb (new)
    Dimm 3 : 0Gb (empty)
    Dimm 4 : 1Gb (original)

    Total shown is 8Gb RAM



    After yet another reshuffle....


    Set A
    Dimm 1 : 2Gb (new)
    Dimm 2 : 1Gb (original)
    Dimm 3 : 2Gb (new)
    Dimm 4 : 0Gb (empty)

    Set B
    Dimm 1 : 2Gb (new)
    Dimm 2 : 1Gb (original)
    Dimm 3 : 2Gb (new)
    Dimm 4 : 0Gb (empty)

    Total shown is 8Gb RAM

    After yet another reshuffle....

    Set A
    Dimm 1 : 2Gb (new)
    Dimm 2 : 0Gb (empty)
    Dimm 3 : 2Gb (new)
    Dimm 4 : 1Gb (original)

    Set B
    Dimm 1 : 2Gb (new)
    Dimm 2 : 0Gb (empty)
    Dimm 3 : 2Gb (new)
    Dimm 4 : 1Gb (original)

    Total shown is 8Gb RAM

    ....I give up! :confused:


    Is it not possible to get the system to see all 10Gb? It seems odd because the system seems to work with 2Gb in as default.. then doesn't allow me to fill in three outta four slots in each bank... What's going on? Can someone shed some light on this?

    I'm using the MacPro 2008, Harpertown

    Thanks You in advance.
     
  2. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #2
    Set A
    Dimm 1 : 2Gb (new)
    Dimm 2 : 2Gb (new)
    Dimm 3 : 1Gb (original)
    Dimm 4 : 1Gb (original)

    Set B
    Dimm 1 : 2Gb (new)
    Dimm 2 : 2Gb (new)
    Dimm 3 : 0Gb (empty)
    Dimm 4 : 0Gb (empty)
     
  3. DualShock macrumors 6502

    Joined:
    Jun 29, 2008
    #3
    See pg 44 of this manual:
    http://manuals.info.apple.com/en/Mac_Pro_Early_2008.pdf

    Note: The memory population rules are different for the 2006/2007 Mac Pro's.
     
  4. Graeme43 macrumors 6502a

    Graeme43

    Joined:
    Sep 11, 2006
    Location:
    Great Britain (Glasgow)
    #4
    in mine i have 2 ram in each of the furthest away slots. i think the mac pro works like this

    first 2 sticks go top slots at the rear
    second 2 go at bottom rear
    third 2 go on the top near
    fourth 2 go on the bottom near
     
  5. UltraNEO* thread starter macrumors 601

    UltraNEO*

    Joined:
    Jun 16, 2007
    Location:
    近畿日本
    #5
    Sorted... Thanks for your help guys.
    I would read the manual but mine's all in Japanese!! :rolleyes:

    [​IMG]
     
  6. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #6
  7. ThirteenXIII macrumors 6502a

    Joined:
    Mar 8, 2008
    #7
    opposite. reverse that.

    it goes A1&2 B1&2 ...then.... A3&4 B3&4 etc.


    the screen shot of the users new placement is the ideal solution.
     
  8. CanadaRAM macrumors G5

    CanadaRAM

    Joined:
    Oct 11, 2004
    Location:
    On the Left Coast - Victoria BC Canada
    #8
    Actually, not quite ideal. If the 2 GB modules were in slots A1 A2 B1 B2, then the machine could do 256 bit access. The smallest RAM should be relegated to the 3 & 4 slots.
     
  9. UltraNEO* thread starter macrumors 601

    UltraNEO*

    Joined:
    Jun 16, 2007
    Location:
    近畿日本
    #9
    The original and default location for ram, when the system arrived was in A1 and B1... so I just assumed the new modules would go in A2 and B2 blah... but that's not the case...

    LOL... Who would of thought? :rolleyes:
     
  10. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #10
    Yes, it can be confusing without documentation. Memory on FB-DIMM based systems is meant to be in pairs, but with the 5400 chipset when only using 2 DIMMs optimal performance can be gained by putting them on seperate risers.
     

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