I've upgraded my iMac's memory/RAM but...

Discussion in 'iMac' started by arionarion, Sep 1, 2011.

  1. arionarion macrumors newbie

    Joined:
    Sep 1, 2011
    #1
    Hello...

    Today I've upgraded my 27" QC 3.1 Ghz 2011 iMac's RAM from 4gb to 8GB.
    Until now I didn't have any problem.
    I also didn't use any video, music or photo editing program yet.

    My question is:
    Physically old and new RAMs don't look like each other but I can note that specification has changed from 4GB to 8GB in "About This Mac".
    Existing RAMs are: On the left darker ones...
    Samsung M471B5673FH0-CH9 1048 2GB 2RX8 PC3 - 10600S-09-10-F2
    Newly added RAMs are: On the right lighter ones...
    Samsung M471B5773DH0-CH9 1108 and 1113 2GB 1RX8 PC3 - 10600S-09-11-B2

    What do you think, do they work fine together?
    Will I have any performance problem or oppositely get any benefit at my video/photo/music editing works?


    Thanks for your answers.
     

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  2. arionarion thread starter macrumors newbie

    Joined:
    Sep 1, 2011
  3. Qwaf macrumors member

    Joined:
    Sep 11, 2010
    #3
    It should be fine as long as you're matching each pair or RAM sticks in the same pair of DIMM slots, just so you're not getting any problems with the whole dual channel memory business.
     
  4. arionarion thread starter macrumors newbie

    Joined:
    Sep 1, 2011
    #4
    Thanks Qwaf...

    Is it corretct matching of placing on the photo?
    or
    Old ones upper line and new ones bottom line? ( or the other way around)
     
  5. Glen Quagmire macrumors 6502a

    Joined:
    Jan 6, 2006
    Location:
    UK
    #5
    http://support.apple.com/kb/HT3918 indicates that pairs are horizontal, so if you position your iMac like in the link:

    Old Old
    New New

    Not:

    Old New
    Old New

    It won't matter which pair is at the top and which is at the bottom.
     
  6. Qwaf macrumors member

    Joined:
    Sep 11, 2010
    #6
    This. Doesn't matter if the new ones are on the top or bottom, but as long as they're matched on the top or bottom line.

    So for example:

    NEW NEW
    OLD OLD

    or

    OLD OLD
    NEW NEW
     
  7. arionarion thread starter macrumors newbie

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    Sep 1, 2011
    #7
  8. apw100 macrumors regular

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    Jan 24, 2010
    Location:
    Jacksonville, FL
  9. err404, Sep 2, 2011
    Last edited: Sep 2, 2011

    err404 macrumors 68020

    Joined:
    Mar 4, 2007
    #9
    You should try to match the RAM in each bank as suggested by others, but cross bank differences shouldn't matter.
    Also, as a general rule, I always run MEMTEST before and after adding new RAM (Google it). It's a bit tricky to get going since you should be booted to single user mode, but it helps to ensure that the system is as stable as possible.
     
  10. RayK macrumors 6502

    Joined:
    Oct 13, 2005

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