2012 i7, overheating, three tones, need opinions

Discussion in 'Mac mini' started by Paco II, Jun 5, 2015.

  1. Paco II macrumors 65816

    Joined:
    Sep 13, 2009
    #1
    I've got a 2012 i7 that will regularly overheat. The way this manifests itself is that the machine will get extremely hot, fans will spin to max, computer will restart, then I will get the repeating three tones (which theoretically indicates a RAM issue). I can unplug the power, replug in, and the computer starts up fine.

    This is what I've tried: reformatting and starting fresh, changing RAM (both slots, twice), using an application to increase fan speeds. Nothing has helped. I even cloned the mac onto a 2012 i5 mini to see if it is software related, but the i5 does not exhibit the same issue.

    Is it a good bet, at this point, that there is an actual hardware issue and worth taking it to the Apple Store? Or am I missing something else to try?

    Thanks.
     
  2. grcar Suspended

    grcar

    Joined:
    Sep 28, 2014
    #2
    You had me at the cloned version does not exhibit the same issue. Take it in. I would be curious to know what the genius bar does and what they charge.
     
  3. Gav2k macrumors G3

    Gav2k

    Joined:
    Jul 24, 2009
    #3
    Have you blown the machine out to remove dust?

    Have you tried a fresh install?
     
  4. Paco II thread starter macrumors 65816

    Joined:
    Sep 13, 2009
    #4
    Yes and yes.

     
  5. Gav2k macrumors G3

    Gav2k

    Joined:
    Jul 24, 2009
    #5
    Well your out of warranty so you could change the thermal paste as its god awful
     
  6. Paco II thread starter macrumors 65816

    Joined:
    Sep 13, 2009
    #6
    Any more info you can share on what to do/how to do it? Thanks!

     
  7. Gav2k macrumors G3

    Gav2k

    Joined:
    Jul 24, 2009
  8. oneMadRssn macrumors 68040

    oneMadRssn

    Joined:
    Sep 8, 2011
    Location:
    Boston, MA
    #8
    I would take it to an Apple store for a diagnosis before changing the thermal paste. It very well could be some other hardware failure on the logic board, and going through the whole thermal paste process could be a waste of time.
     
  9. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #9
    The restart may or may not be heat related, so before bothering with thermal paste I'd use iStat Pro to get accurate readings of your temperatures and compare them to maximum allowed. If you are not going past your temperature maximums, then there is some other hardware problem.
     
  10. rwprater macrumors newbie

    Joined:
    Jul 14, 2015
    Location:
    MidWest
    #10

    ======

    Apparently a lot of people have this problem with the i7 2012. When running Handbreak to convert a movie my Mini would run at %100 CPU for over an hour at 102C degrees. Sometimes peaking at 105C. In addition, the temps of the 4 cores should have been close to one another but core-1 was consistently 7 degrees higher than the others. I tried a lot of things including taking the bottom cover off and blowing a fan toward at it but that didn't help. With core-1 being so high I wondered if the heatsink was making good contact.

    I took the Mini apart, removed the heatsink, and cleaned the heatsink compound off. Afterward I put the heatsink back on with the spring-loaded screws exactly as it was WITHOUT heatsink compound - then I held up the board edgewise to the light and found that there was a partial gap between the heatsink and CPU (I could see light between them). The heatsink on the graphics chip wasn't touching the chip at all. I could press down on the heatsink near the middle and make it contact both chips. Apparently the spring loaded screws were just not strong enough to press the heatsink down on to the CPU and graphics chip. In addition, the screws have a shoulder that will not permit you to tighten them down more.

    I experimented with other screws for the heatsink. I had an assortment pack of laptop screws that I used in place of the spring loaded screws. I snugged them until the heatsink contacted the CPU & graphics chip (I did not over-tighten). I found that I could still use all the spring loaded screws except in one position. I left a laptop screw in the screw position near the outside of the dog leg of the heatsink where the plastic cowling hooks in. I took the heatsink off again and re-applied heatsink compound and reassembled using the one laptop screw in the position mentioned. Because of this I didn't install the plastic cowling that fits over top of the heat pipes. Kinda looked unnecessary anyway.

    After reassembling and testing again with Handbreak I found my CPU temps were down about 24C degrees. When I take my bottom cover off during the handbreak test the temps drop to 74C degrees (no outside fan). In addition, the temps for the 4 cores vary a bit as you would expect but are within a couple degrees of the other cores. This tells me that the heatsink is now making better contact with the CPU.

    That was my experience. Hope it helps.
    Randy
     
  11. grcar Suspended

    grcar

    Joined:
    Sep 28, 2014
    #11
    Awesome explanation. $600 billion dollar company could not figure out they designed/built flawed stuff.
     
  12. VanillaCrackerC macrumors newbie

    Joined:
    Jun 8, 2013
    #12
    I have the same memory init problem (three tones) after firmware update. MM 2012 i5
     

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