Late-2009 iMac ram options

Discussion in 'iMac' started by sensei-, May 10, 2013.

  1. sensei- macrumors newbie

    Joined:
    May 9, 2013
    #1
    Have been trying to get some information about iMac ram compatibility; but have not been very successful.

    I understand that late 2009 (27" i7 CTO) officially supports 16gb, but can handle up to 32gb unofficially.

    My original machine had 2x 2gb 1066mhz DDR3 ram. I added another 2x 2gb 1333mhz DDR3 ram. About this mac would give me "8gb 1066mhz DDR3", so the newer ram was running at the lower speed. However, when I sold the 2 sticks of 1066mhz ram, I notice my mac to be reporting "4gb 1333mhz DDR3"

    As I intend to add 16gb or 32gb DDR3 ram, does this mean that my system can support 1333mhz ram? Or is it just recognising that I have added a slightly faster version in the slots.

    Which leads me to a couple of questions.

    1) Will it be better to run 1333mhz ram?
    2) What ram should I run in my system to maintain system capability?
    3) Is there any difference between 16 and 32gb of ram? I understand more never hurts, but is there a point of diminishing return.

    I have narrowed my list of ram to as follows:

    Kingston KVR1333D3S9/8G DDR3 1333 ($59/stick)
    Corsair CMSX8GX3M1A1600C10 8GB DDR3 ($65/stick)
     
  2. Dadioh macrumors 65816

    Dadioh

    Joined:
    Feb 3, 2010
    Location:
    Canada Eh?
    #2
    With the i7 the memory controller is built into the CPU so it does detect and run at the lowest speed of the installed RAM modules. So even a single stick of 1066MHz with 3 sticks of 1333MHz will cause the memory bus to run at 1066MHz.

    I put in 4 X 4GB 1333MHz in my late 2009 i7 2.8GHz and it runs rock solid. I have heard conflicting reports whether it does support 32GB but I personally find 16GB to be lots.

    But let us know how it goes if you get 32GB running.
     
  3. smokeyrabbit macrumors 6502

    Joined:
    May 19, 2005
    Location:
    Escape from New England
    #3
    I have a late 2009 i7 CTO as well but with 12 GB RAM. The ONLY time I max out the eight cores is encoding with Handbrake. I have 32 days of uptime right now and always have 2 users' iTunes, iPhoto, and a Plex media server running, I still have 2-4 GB free. The HDD is the bottle neck in the UI "snappiness". Unless you are constantly editing large photos or running multiple virtual machines at the same time you won't notice any improvement from 16 to 32 GB. Even things like rendering a slideshow from iPhoto are limited by the HDD rather than CPU or RAM.

    I have put several different HDD's in the iMac over the last couple years due to failures and power outages, and I'm this close to replacing the optical drive (since I have an external BR writer) with a SSD and going with a Fusion drive to bring it back up to speed.
     
  4. thedeske macrumors 6502a

    Joined:
    Feb 17, 2013
    #4
  5. sensei- thread starter macrumors newbie

    Joined:
    May 9, 2013
    #5
    yup, i understand the first bit if i do mix/match ram modules. however, i take it that if i did have all 1333mhz modules, it might actually run at 1333mhz? or would it revert back to 1066mhz because the mac originally supported 1066mhz.

    interesting. i run nothing nearly as intensive as you do, and i feel that my machine can be sluggish at times.

    things i currently run on my system across 2 physical monitors and 5 spaces
    mail; thunderbird; reeder; safari; firefox; imessage; calendar; reminders; preview; itunes; adium; utorrent; VLC; eyetv; word; excel; photoshop; and dreamweaver

    i do intend to keep this machine until it kicks the bucket. which speed ram i get will depend on how much ram i decide to use. 16gb is available in 1066mhz but 32gb is not.
     
  6. Dadioh macrumors 65816

    Dadioh

    Joined:
    Feb 3, 2010
    Location:
    Canada Eh?
    #6
    It will run at 1333MHz if all modules are rated at that speed.
     
  7. thedeske macrumors 6502a

    Joined:
    Feb 17, 2013
    #7
    It is from OWC, but overpriced.
     
  8. sensei- thread starter macrumors newbie

    Joined:
    May 9, 2013
    #8
    yeah i wont be buying ram from OWC. Still not entirely sure if buying the kingston ram will be guaranteed to work (since my local parts supplier wont accept returns for incompatibility). for some reason, i have a feeling it will work.
     

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