Memory Installation for Mac Newbie - Sorry Long Winded Post

Discussion in 'Mac Pro' started by Siron, Apr 19, 2008.

  1. Siron macrumors 6502

    Siron

    Joined:
    Feb 4, 2008
    Location:
    North Carolina
    #1
    I know there have been a lot of posts about installing additional memory - I even watched the installation video over at OWC. OWC video shows two factory 1GB memory sticks - one in Slot A of the upper riser board and one in Slot A of the lower riser board. It says to move the module from Slot A of the lower riser board and install it in Slot B of the upper riser board to make a matched pair.
    But here's the question. I have 4GB of RAM - two 1GB modules in Slots A&B of each riser board from the factory (I know - I know - I should have ordered it with the stock RAM and purchased the extra at less than the exorbitant prices Apple charges - but that's another story). I want to add 4GB more (two 2GB modules):

    1. Move the two 1GB factory modules from Slots A&B of the lower riser board into Slots C&D of the upper riser board and then install the two new 2GB modules into Slots A&B of the lower riser board (just as the OWC video implies)?
    2. Leave the factory modules where they are and install one 2GB module in Slot C of each riser board to provide a "balanced" 4GB on each riser board?

    Options #2 seems to provide a "balanced" module location (4GB in the upper riser board and 4GB in the lower riser) so the four cores on each CPU can access an equal amount of memory for optimum performance. - but I have read that you need to install the new modules in matched pairs - but does that mean put them together on the same riser board? In the OWC video, if the two new modules were a matched pair then why wouldn't they be put one in each riser board just like the factory modules????
    Sign me :confused:.
    Alan
     
  2. tyr2 macrumors 6502a

    tyr2

    Joined:
    May 6, 2006
    Location:
    Leeds, UK
    #2
    Option 2 won't work, as you say they must be installed in pairs. That is slots A&B or slots C&D on each riser card. You must have either 0,2 or 4 DIMMS on each riser.

    Go for Option 1 that makes the most sense. You want to put your two 1GB pairs on the same riser and then leave the other riser free for the 2GB pair. This should give you the best performance with that combination of DIMMS.
     
  3. krye macrumors 68000

    krye

    Joined:
    Aug 21, 2007
    Location:
    USA
    #3
    I was going to throw in my 2 cents about installing memory, but I've grown tired of explaining it. After all, it's spelled out in plain English in the user manual.
     
  4. eluk macrumors 6502a

    eluk

    Joined:
    Dec 14, 2006
    Location:
    East London, UK
    #4
    Hurrah!!
     
  5. Siron thread starter macrumors 6502

    Siron

    Joined:
    Feb 4, 2008
    Location:
    North Carolina
    #5
    Thanks for your help!!! I wouldn't post a question if I had read the instructions and was no longer confused. The manual assumes you have two 1 GB modules. As I explained in my post I'm confused because I have four 1 GB modules.
     
  6. CanadaRAM macrumors G5

    CanadaRAM

    Joined:
    Oct 11, 2004
    Location:
    On the Left Coast - Victoria BC Canada
    #6
    Did you look in the Guides (under the Guides tab at the top of the window)?

    Guides : Hardware : Installing RAM

    Conventionally, the risers are known by letter, and the slots by number. The Pairs are formed on sequential slots on the same riser, not across both risers.

    Fill the slots in this order, starting with your largest capacity modules.

    A1 A2

    B1 B2

    A3 A4

    B3 B4
     
  7. Siron thread starter macrumors 6502

    Siron

    Joined:
    Feb 4, 2008
    Location:
    North Carolina
    #7
    Great - so my two 2GB sticks go in A1 and A2 and the factory sticks go in B1, B2, A3, and A4.
    Thanks for the help CanadaRAM. One more question - if you ordered a machine with just 2Gb would it be in A1 and A2 (a "matched pair") ? With my configuration then - I have to ensure that I keep the "matched pairs" together and not mix them up - right?
    Alan
     

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