Adding ram to a 2.8 mac pro: another ram question!

Discussion in 'Mac Pro' started by nicolasmasset, Apr 28, 2009.

  1. nicolasmasset macrumors regular

    Joined:
    May 25, 2007
    Location:
    Belgium
    #1
    Hi,

    I have the stock 2x1 and just ordered matched 4x2gb for a total of 10gb.
    Now, I probably won't be needing 10gb for my audio work, so my question is, should I leave the stock ram out for the added benefit of the quad channel ram thingie? Because, according to this report, the 10gb config gives 6.8 throughput vs the 6.5 of the 4x2gb! I thought 4 or 8 slots filled should be faster? What gives??

    Regards,

    Nicolas
     
  2. sigmadog macrumors 6502a

    sigmadog

    Joined:
    Feb 11, 2009
    Location:
    near Spokane, WA
    #2
    Not sure what would be faster, but I'm inclined to include all the RAM you can. Just make sure that, if you do keep using the 1GB sticks, that they are together on the same card.

    I ordered 12GB (6x2GB) to go with the stock 2x1GB sticks, but didn't move the bottom 1GB to the top card next to the other 1GB.

    Instead of this (proper) configuration:

    TOP: 1GB • 1GB • 2GB • 2GB
    BOTTOM: 2GB • 2GB • 2GB • 2GB

    I had this (improper) configuration:

    TOP: 1GB • 2GB • 2GB • 2GB
    BOTTOM: 1GB • 2GB • 2GB • 2GB

    As a result, the computer only recognized 12GB RAM, not the 14GB I had installed. Once I corrected the matter, placing the 1GB sticks together on the same board, everything was (and is) fine.
     
  3. Billydelp4 macrumors regular

    Joined:
    Feb 29, 2008
    #3
    Put your largest ram sticks on the top riser in slot 1 & 2. Then move to bottom riser slot 1&2. Then move back to top then finally back to bottom. you want your largest sticks being accessed first then the smaller last.

    Billy
     

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  4. nicolasmasset thread starter macrumors regular

    Joined:
    May 25, 2007
    Location:
    Belgium
    #4
    Ok thanks guys, I did the following:

    1st riser = 2x2 + 2x1
    2nd riser = 2x2 + empty

    All seems to be working fine!
     
  5. select macrumors newbie

    Joined:
    Apr 14, 2009
    #5
    Hi guys,
    I apologize if i'm entering the discussion, but yesterday i've ordered my first ram expansion from kingston (2gb=2x1) to be added to the current standard (2x1) for my mac pro 2.8, what is the ideal arrangement?

    Solution1:
    1st riser = 4x1
    2nd riser = empty

    Solution2:
    1st riser = 2x1
    2nd riser = 2x1

    Thank you
     
  6. Billydelp4 macrumors regular

    Joined:
    Feb 29, 2008
    #6
    Follow the diagrams above. Fill slots 1&2 on top and bottom risers
     
  7. sigmadog macrumors 6502a

    sigmadog

    Joined:
    Feb 11, 2009
    Location:
    near Spokane, WA
    #7
    You'll need a pair on each riser.

    Also, I'm going to take Billydelp4's advice and re-orient my RAM cards to place the higher RAM in the first two slots of each riser. I hadn't heard of that technique before. I wonder if I'll notice a slight boost?
     
  8. Billydelp4 macrumors regular

    Joined:
    Feb 29, 2008
    #8

    Check barefeats for optimization benchmarks. I'm pretty sure the difference is miniscule but hey better is better right? Fill us in if you notice any difference.
     
  9. Tesselator macrumors 601

    Tesselator

    Joined:
    Jan 9, 2008
    Location:
    Japan
    #9
    If you apps and OS are frequently accessing memory locations on near the 4GB barrier (in layman's terms) then you might. If memory access is "busier" at the 10GB line and your your 2GB are at the end then having them last will be slower.
     

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