New RAM for iMac

Discussion in 'iMac' started by photogpab, Dec 22, 2011.

  1. photogpab, Dec 22, 2011
    Last edited: Dec 22, 2011

    photogpab macrumors 6502

    photogpab

    Joined:
    Jun 21, 2010
    #1
    Just ordered a new 27" 3.1 GHz i5 iMac, it arrives today, and I ordered RAM from Crucial to bump it up to 12GB... it also arrives today!

    However, I was reading in another thread that if you install RAM of different capacities it disables something, or it actually slows down anywhere up to 10% because they cant communicate to each other? or something like that?

    can anyone explain further?

    I ordered two 4GB Cards for the two empty slots that will be in the iMac. Bumping it up to 12GB.

    this is what i bought:

    http://www.crucial.com/store/partspecs.aspx?imodule=CT2KIT51264BC1339
     
  2. simsaladimbamba

    Joined:
    Nov 28, 2010
    Location:
    located
    #2
    It has to do with dual channel support, but since you have two 2 GB and two 4 GB RAM modules, that will not be a problem, and you computer will not slow down, but if you would use four 4 GB sticks, you might see a 10% speed increase in RAM intensive applications.
     
  3. photogpab thread starter macrumors 6502

    photogpab

    Joined:
    Jun 21, 2010
    #3
    so if i buy two more of those 4GB cards I can replace the 2GB Cards that came with the iMac correct?

    and that would be 16GB and there would be no dual channel support issue.. or whatever its called?

    Im so stupid... at the time that I ordered I opted to buy two 4GB cards because they were $45 for the pair and it would bring me up to 12GB. the next thing they had were two 8GB cards for 16GB but they were priced at $200!

    i didnt realize i could just buy two more of the 4GB and replace the cards that already come with the iMac, and then I would have four 4GB cards in the iMac for a total of 16GB but it would only cost me about $90 instead of the $200 for the two 8GB cards.
     
  4. TEG macrumors 604

    TEG

    Joined:
    Jan 21, 2002
    Location:
    Langley, Washington
    #4
    The issue is that you need to have matched pairs, to get good results. However, those pairs don't have to match the other pair in the machine. If all 4 slots have the same capacity RAM, that will work best, but you shouldn't have any issues. If instead you were upgrading with a 2GB and a 4GB, there might be issues.

    TEG
     
  5. photogpab thread starter macrumors 6502

    photogpab

    Joined:
    Jun 21, 2010
    #5
    i think i'll buy two more of the 4GB cards next week and replace the two 2GB cards. then I'll have 16GB.
     

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