21 IMac RAM configuration

Discussion in 'iMac' started by Jurph, Nov 10, 2011.

  1. Jurph, Nov 10, 2011
    Last edited: Nov 10, 2011

    Jurph macrumors newbie

    Nov 10, 2011

    I have a late 2009 21.5'' IMac that cam withe the standard 4Gb RAM (2x2GB Modules)

    Now I bought two additional 4Gb RAM modules, so I have 12GB in total.

    What ist the correct disposition of the modules in their sockets that allows to preserve dual channel capability?

    Right now I have inserted them like this:

    BANK 0/DIMM0 4 GB
    BANK 1/DIMM0 2 GB
    BANK 0/DIMM1 4 GB
    BANK 1/DIMM1 2 GB

    is this correct?

    Also, is there a way to check if my mac is really running in dual channel?

    Thank you for your responses :)
  2. Veryold macrumors newbie

    Aug 16, 2011
    You are correct. The slots are in horizontal pairs and you will have the 2x2 in the top slots and the2x4 in the bottom slots.
    I do not believe there is any way of knowing if the memory is running in dual channel. In your set up it should be . The difference is not all that great and has been estimated at 5%. With the extra ram you should have noticed a big increase in performance.

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