1866MHz Ram For iMac

Discussion in 'iMac' started by zarzonis, Jun 27, 2013.

  1. zarzonis macrumors member

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    #1
    Hi i just bought a 27" iMac and i want to uprgade the Ram from 8GB to 16GB. I will use 4 of 4GB each. I want to buy 1866MHz Ram. Will 1866 Ram work on iMac and also run at 1866MHz?If yes, will i have any problem? If it's not then i'll buy 1600MHz.
    Thank you in advance.
     
  2. Bear macrumors G3

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    #2
    1600MHz is the fastest memory the iMac memory will support. That's straight from Intel's website for the processors that the 2012 iMac uses. 1866MHz memory will not run any faster than the 1600MHz memory in the iMac and depending on the CL timing, could be slower when clocked down to 1600MHz. And there's always a chance that it won't work at all.
     
  3. zarzonis thread starter macrumors member

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    #3
    So i'll buy 16GB of 1600MHz Ram for my new iMac. Thank you so much for your reply.
     
  4. Chippy99 macrumors 6502a

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    #4
    Bear has given you the safe advice. But not necessarily the correct advice.

    Older Mac Minis used to run 1866MHz ram at 1866MHz with no adjustment required. As I understand it, the 2012 Mini's don't do that, but unless anyone has actually tested it in a 2012 iMac, then I am not sure we know for certain.

    If indeed it will auto-set the timing to 1866MHz, it could be a useful speed boost and would in all probability be 100% stable. (It's a standard Intel Z77 Ivybridge chipset which will very happily run memory at 2000MHz and over.)

    Someone needs to drop some 1866MHz ram in to find out!
     
  5. Bear macrumors G3

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    #5
    The question becomes if the chipset supports the faster memory are you gaining any benefit from it (and how much) if Intel states that the processor supports 1333MHz and 1600MHz memory? Or is Intel's website wrong?
     
  6. Chippy99 macrumors 6502a

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    #6
    Agreed about whether it's worth it. As to whether Intel's website is wrong, I suspect you are being arsey and full well know the answer. That does not mean it does not work though, does it. Gigabyte, MSI, Asus, Abit, Chaintech, Asrock, EVGA and every other motherboard manufacturer I can think of would not put 1866 2000 2133 and every other setting in the bios if it didn't work would they. There isn't an i7 in existance that won't run memory successfully at 1866 with the right ram, voltages and timings. The only questions are whether the board will automatically select 1866, because if it will not you have no way of forcing it on a Mac, and (b) is it worth it.
     
  7. zarzonis thread starter macrumors member

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    #7
    Sorry for the late answer. I know that an ivy bridge chipset and specially an i7 will support 1866mhz RAM. My hackintosh right now has over 2000mhz RAM with a gigabyte z77x ud5h and an i7 3770K. My question is if the "BIOS" of the iMac will automatically adjust the RAM at 1866MHZ. I think that in case that it doesn't adjust at 1866MHZ it will underclocked at 1600MHZ but I'm not sure.
     
  8. Chippy99 macrumors 6502a

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    #8
    That's the point. As I said above, older Mac Minis would automatically clock at 1866 if you put 1866 ram in it. Newer Minis stay at 1600.

    Until someone installs 1866 ram and goes into windows and runs CPUz, I guess we don't know what speed 1866 ram will run at in a 2012 iMac.
     
  9. MorpheusXX macrumors newbie

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    Mar 27, 2014
    #9
    I just put 1866Mhz memory into my Late 2012 27'' iMac with i5 processor. Its now mixed with the standard 1600Mhz memory and working fine, although it is only running at 1600Mhz.

    I used KHX1866C11S3P1K2/8G Kingston memory.
     
  10. Chippy99 macrumors 6502a

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    #10
    Not suprising it's running at 1600 given you have 1600 and 1866 mixed in there.

    We have established elsewhere (after this thread was started) that 1866 ram does indeed run at 1866 in a 2012 iMac.
     
  11. ender78 macrumors 6502

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    #11
    I am using GSKILL 1866 memory in my 2013 iMac.
     
  12. Chippy99 macrumors 6502a

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    #12
    I am sure you are. But the relevant point is what speed is it running at?
     
  13. ender78 macrumors 6502

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    #13
    It is running at 1867
     

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  14. SaSaSushi macrumors 68040

    SaSaSushi

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    #14
    Do not be the least bit surprised if you end up with kernel panics if you ever increase the system to 32GB. See this thread for more information.
     
  15. Weaselboy Moderator

    Weaselboy

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    #15
    I believe that is just showing you have installed 1867Mhz RAM, not necessarily that it is running at that speed.
     
  16. Chippy99 macrumors 6502a

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    #16
    Nope, it shows the speed it's running at, not what is installed.
     
  17. Weaselboy Moderator

    Weaselboy

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    #17
    How are you certain of this?
     
  18. Chippy99 macrumors 6502a

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    #18
    Because if you install 16GB of 1600MHz CL10 ram alongside 1600MHz CL11 Apple ram, it shows it running at 1333MHz in the System Report.

    1333MHz is the fastest speed the stock ram can run at CL10, so it drops the speed down to that rate. But the point is, it's all 1600MHz memory, but it shows the rate it's running at.
     
  19. Weaselboy Moderator

    Weaselboy

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    #19
    Got it. Thanks for the follow up.
     

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