2017 iMac RAM Issues

Discussion in 'iMac' started by jagolden, May 23, 2019.

  1. jagolden macrumors 6502a


    Feb 11, 2002
    Strange issue happening and looking for some guidance.
    A few months ago I purchased a Refurbed i5 5K 27" iMac from the Apple Store. It is the base model so only came with 8g of RAM and the 1tb Fusion Drive.
    All runs perfectly UNTIL I install additional RAM. I copied and pasted the RAM specs directly from the Apple tech notes to do my search.

    Initially I installed 2 16g OWC modules. They worked for about 2 months then seemed to cr*p out and the computer would not even start up. I removed the OWC modules and everything was back to running and starting OK.
    So then I bought another brand, Timetec, I believe. Installed those and worked great for 2 days. Then I shut the computer down and it would not start back up. Removed those two RAM modules, and as expected, the computer starts and runs fine.

    I even removed the Apple memory and installed the 4 16g OWC and Timetech modules, again, no startup, nothing, nada.

    It’s not like the computer is slow, but I’d like more RAM. I am using an external ssd boot disk for startup and applications.

    Any thought or others’ experience with this issue?

  2. LesInSTL, May 23, 2019
    Last edited: May 23, 2019

    LesInSTL macrumors newbie

    Sep 14, 2016
    I began experiencing the same issue with my 19,1 model earlier this week. I swapped out the 2x4GB modules for 2 OWC 16GB modules and everything was working fine until Monday. Would not power on at all. Put the original apple memory back in and it booted right up.

    I did run the upgrade to 10.14.5 when I left for work and it was still updating. Came home and it was "dead". I really don't think that it was the OS upgrade that is causing the problem since it works fine with the apple memory.

    Very frustrating

    UPDATE: After following the complete instructions for doing a SMC reset it resolved my problem.
  3. jagolden thread starter macrumors 6502a


    Feb 11, 2002
    Yes very frustrating. At least the upgrade modules worked initially, but like now, install them and no power up.
    I’m considering calling Apple, then maybe getting in for the AppleCare+ service. But who can afford to be without their computer for however long it takes them to figure it out.
    At least the internal drive is cloned and all other files are kept on externals plus a Timemachine.

    Thanks for the response and letting me know I’m not the only one or crazy.

    The Apple sticks are in slots 1 & 3. Does ram need tp go in 1, 3, 2, 4 slot order. I am thinking of giving it one more go and putting 1 stick each of the new ram into slots 1 & 3. At least this would give me 32g (if it woks!)
  4. LesInSTL macrumors newbie

    Sep 14, 2016
    My configuration has the 32GB (2x16GB) in slots 1 and 2 and the original apple memory (2x4GB) in slots 3 & 4. Once I had it I the configuration I disconnected the power cord and then held the power button down for 15 seconds (the part I didn't originally do) and then connected the power cord and started up. Everything has been working well since then.
  5. Fishrrman macrumors P6


    Feb 20, 2009
    If you have a computer that is working properly,
    and then...
    Put new RAM into it,
    and then...
    The computer STOPS working properly,
    The first thing to do is take the RAM OUT and see if the computer starts working properly again.

    If it does, that should tell you something.
  6. jagolden thread starter macrumors 6502a


    Feb 11, 2002
    As in my original post I did just that multiple times. Works fine with the basic 8g of Apple ram but not with the third party ram.
    --- Post Merged, May 24, 2019 ---
    Thanks so much for the suggestions! I utilized your instructions but removed the 4g Apple ram sticks altogether and installed the 4 sticks I had bought. Did the cord and button thing and all seems to be working fine now and instead of 40g of ram I now have 64g. Combined with the external ssd the computer hums right along.
    It still does take about 30 seconds longer to start up.
    Again, thanks for taking the time to help me out!
  7. gilby101 macrumors regular

    Mar 17, 2010
    For best performance, the usual recommendation is to have identical sticks in slots 1 and 3, and in 2 and 4. In your case 2x16 in slots 1 and 3 and 2x4 in 2 and 4 OR 2x16 in slots 2 and 4 and 2x4 in 1 and 3.

    Holding the power button for 15 seconds is a new one on me. I have always just left the power cord disconnected for 15 seconds (without doing anything with the power button). As per https://support.apple.com/en-us/HT201295. I will try your instructions next time I need to do an SMC reset.
  8. theluggage macrumors 68040

    Jul 29, 2011
    Assuming its a 2017 model iMac (although I think its the same for all 5k models), for optimum performance, RAM needs to be added in pairs of matching sticks, with one pair in slots 1 & 3 and another in slots 2 & 4. That will enable 'dual channel' mode. That doesn't mean that other combinations won't work, just that they won't run in 'dual channel' mode which will have a measurable performance hit.

    Sounds like a good diagnostic step to rule out the possibility of one or both of the other slots being faulty.

    PS: AFAIK neither OWC or Timetech make their own RAM sticks - only a few companies actually make RAM sticks and only about 3 actually make the chips, so it's entirely possible that they're both selling the same product and very likely that they're built with the same chips.

    For what its worth, I've usually gone to crucial.com - the consumer arm of micron who do make their own RAM (and one of the brands used by Apple) and used their online tool to select an 'upgrade kit' sold specifically for the particular model of Mac. (Disclaimer, I live in the UK where false advertising isn't a human right, so having it 'in writing' that the chips are compatible counts for something).
  9. jagolden thread starter macrumors 6502a


    Feb 11, 2002
    Ah well, it was a short lived victory.
    I installed 16g OWC sticks in slots 1 and 3, then 16g Timetech sticks in slots 2 and 4 for a total of 64g. Did the button and unplug thing. Worked great, fast. Restarted a few times and all was well.
    I’ve had the unit running for about 5 days straight. Today I shut it down. When I went to power it on, no go, zero response, black screen. When I hit the power button all I could hear was the initial whir of the external SuperDrive.
    Had to take all ram out and reinstall. Did the button and unplug thing. Still no go.
    I ended up reinstalling the original 2, 4g Apple sticks in slots 1 & 3, then installed the 2, 16g OWC sticks in slots 2 & 4.
    Did button and unplug thing and it started right up, but now only have 40g ram.
    Restarting the computer seems to work, but not shutting down then starting up.
    Just so disheartening.

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8 May 23, 2019