Dual Channel Memory Arrangement - Late 2013 iMac

Discussion in 'iMac' started by DOlsson, Nov 4, 2013.

  1. DOlsson macrumors member

    Joined:
    Feb 3, 2007
    #1
    Good afternoon all,

    I was in Windows today on my iMac (via bootcamp) and I noticed that when I open up CPU-Z it's stating that my memory configuration is in Single mode. Should it not be in dual channel mode? There are currently two 8GB modules installed.

    Perhaps I have modules in the wrong slots? (Apple installed them for me before I picked the computer up in store).

    Does anyone have a definitive answer as to which slots (from top to bottom) the modules should be installed in?

    Or maybe everything is fine and I'm misreading what CPU-Z/CPUID is saying. See attachments below.

    Thanks again!
     

    Attached Files:

  2. Bear macrumors G3

    Joined:
    Jul 23, 2002
    Location:
    Sol III - Terra
    #2
    Hard to tell from what you posted. In OS X, in the System Information Utility, post a screen shot of the memory from there. I'm attaching a screenshot showing what you should post.
     

    Attached Files:

  3. DOlsson thread starter macrumors member

    Joined:
    Feb 3, 2007
    #3
    Thanks, will do when I'm home and not connecting remotely.

    However, I found a thread that seems to have beaten this topic to death. I'll post the link below. But based on this long read, I think I know what I need to do (or what to check when I get home).

    Here's the thread
     
  4. DOlsson thread starter macrumors member

    Joined:
    Feb 3, 2007
    #4
    Solved!

    Ok, so I got home and popped open my memory bay and this is what I see.

    The smart guys at the Apple store installed the ram like the little drawing below.


    (Top of computer)

    ================== (8GB)
    ================== (8GB)
    ----------------------- (empty)
    ----------------------- (empty)

    (Bottom of computer)


    This resulted in my CPUZ application stating the memory was in "Single" mode.

    I then rearranged the modules to look like this:


    (Top of computer)

    ----------------------- (empty)
    ================== (8GB)
    ----------------------- (empty)
    ================== (8GB)

    (Bottom of computer)


    Now, CPUZ is reporting "Dual" for the channel, and I also notice that the Command Rate (CR) is reporting 1T vs 2T as before - so that's awesome!

    Just thought I'd share my results.

    Thanks!
     

    Attached Files:

  5. Johnf1285 macrumors 6502a

    Johnf1285

    Joined:
    Dec 25, 2010
    Location:
    New Jersey
    #5
    I noticed this too when I upgraded the memory in my 2013 27" (although slightly different).

    "slot 1" ram (toward the top)
    "slot 2" empty
    "slot 3" ram
    "slot 4" empty

    I mimicked this when replacing the two stock 4gb sticks with two aftermarket 8gb sticks.

    Reminds me of the PC building days.
     
  6. Bear macrumors G3

    Joined:
    Jul 23, 2002
    Location:
    Sol III - Terra
    #6
    Why didn't you just add the memory instead of replacing it. That would've gotten you 24GB.
     
  7. Johnf1285 macrumors 6502a

    Johnf1285

    Joined:
    Dec 25, 2010
    Location:
    New Jersey
    #7
    I prefer to keep the same capacity, size, brand, etc., even across the board.

    The new ram has faster timings with 9-9-9-28.
     
  8. Bear macrumors G3

    Joined:
    Jul 23, 2002
    Location:
    Sol III - Terra
    #8
    Ahh the timing difference I can understand.
     

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