Memory arrangement help?

Discussion in 'Mac Pro' started by babbler, Nov 19, 2007.

  1. babbler macrumors member

    Apr 15, 2006
    I have a 4-core Mac pro approx. 6 months old.

    It was bought with 2Gb RAM. This was arranged with 2 x 512 on each memory card. The RAM on the upper card has failed. As a temporary fix I moved the 2 x 512 from the lower card to the upper so that it ran OK with 1Gb.

    The original supplier has now replaced the 2 x 512 which failed with 1 x 1Gb, He says I should add this to the top card. This would leave 2Gb on the top and nothing on the lower card. This does not seem right. I read somewhere that you should spread RAM between the cards to maximise the processor efficiency.

    What should I do ?

  2. Sean Dempsey macrumors 68000

    Sean Dempsey

    Aug 7, 2006
    I don't think a Mac Pro can have an odd-number of ram chips.

    And, you should balance them between the cards.
  3. CanadaRAM macrumors G5


    Oct 11, 2004
    On the Left Coast - Victoria BC Canada
    Not quite --

    RAM must be installed in pairs - if you have 2 RAM modules (2 x 1 Gb) the put them in Riser A slot 1, Riser A slot 2 -- do NOT balance them between the 2 risers.

    If you have 4 RAM modules, put them in A1 A2 B1 B2

    I think what Sean meant to say was if you have 4 identical RAM modules, then putting them in the corresponding slot pairs in both risers - A1 A2 B1 B2 - gets you a very small speed improvement from 256 bit access.

    MR Guide to Understanding Intel Mac RAM

Share This Page