1 2 Previous Next 24 Replies Latest reply: Nov 9, 2013 12:36 PM by Sasparilla256 Go to original post
  • 15. Re: iMac 27" runs VERY hot - too hot to touch.
    Kirk McElhearn Level 2 Level 2 (155 points)

    Did you get your replacement? I'm still trying to figure out my problem. It came back from repair - for the second time - and the technician not only did not smell anything burning, as I did, but didn't get temperatures anywhere near as hot as me. (My secondary heatsink got up to 89 C yesterday in a test.)


    In my case, it's not a question of a heat as much as the burning smell. It seems that above a certain temperature something starts cooking, but the technician couldn't get those temperatures. Working with an AppleCare technician, I've been trying to figure out why.


    Yesterday, I ran tests using the exact same parameters as the repair technician: same user account, runinng Handbrake, with no peripherals attached. And my temps were around 20 degrees higher than his. I'm pretty flummoxed here - could it have something to do with electricity? I've checked my voltage, and it's around 238, which shouldn't be a problem (standard is 230, but you can get +/- 10% according to the electric company). I can't see what colud be different between my office and the technicians workshop (other than the fact that they're in a larger room, but the ambient temps in both cases are similar).


    If the next round of tests doesn't find a solution, I'm going to sell this iMac. The technician said that, for him, it's in perfect condition, so I have no qualms about selling it. I'll get a tricked-out Mac mini and 27" cinema display to replace it.

  • 16. Re: iMac 27" runs VERY hot - too hot to touch.
    CRM-114 Level 1 Level 1 (20 points)

    Yes, received replacement. Sorry, just didnt get round to posting.


    Put iMac through some heavy processing and temps about comparable though just a tad lower.


    LCD Proximity was a few degrees lower

    Secondary Heatsink was about the same as before

    No temps leaping too close to or beyond 90


    Top of iMac does get very hot. Top half of the back warm to hot but not as boiling as previous. This one does run somewhat cooler on the shell. As before it is the top left rear (when facing screen) where the PSU sits that throws out most of the heat when processing.


    So I'd have to concur with Apple that these devices do run hot on the outer casing, and I'd have to say that the previous was fine and it was just me being overly worried, there was no need to return. This one has a 'clicky' power button which is just plain annoying!


    It sounds like you have something not quite built right internally. That's just not what one expects from Apple. I'd guess that your Mac would last but the worry is that something will fry - I'd probably want to sell it too. These are premium quality products and shouldnt really have little issues. Even my little clicky power button makes me want to return it - I'm a bit of a perfectionist and it's all got to be right.


    Good luck with next batch of tests, though sounds like you've already decided that selling it would be the thing to do.

  • 17. Re: iMac 27" runs VERY hot - too hot to touch.
    Michael C M Level 2 Level 2 (205 points)

    Just adding some more stats to the pool.


    These are the maximum temperatures reached when running all 4 cores (8 threads at 100% CPU) for over 3 hours. As you can probably see by the temps the process is CPU intesive but not so GPU intesive.


    Model: Late 2011 iMac 3.4 GHz i7


    CPU: 66 (all temperatures in degrees Celsius)

    Ambient: 16

    GPU Diode: 44

    GPU Heatsink: 40

    Mem Controller: 53

    Optical Drive: 31

    Power Supply 2: 69


    CPU Fan: 1185 rpm (939 rpm when idle)

    Hard Drive: 1299 rpm

    Optical Drive: 1149 rpm


    66 Celcius seemed really high compared to most of the stats on here - 150 Fahrenheit.


    I wanted some benchmarks before sending this computer back - it is one of the many with a darker line (1 cm in height) about 2 cm up from the bottom of the screen (just above the dock really). Easiest to see with a solid colour background.

  • 18. Re: iMac 27" runs VERY hot - too hot to touch.
    Michael C M Level 2 Level 2 (205 points)

    Also, most processors have the maximum recommended temperature available.


    The Tcase for the 3.4 GHz i7 for example is 72.6 degrees Celcius. So as long as the case is keeping its temperature below that no damage is being done (to that component).

    http://ark.intel.com/products/52214/Intel-Core-i7-2600K-Processor-%288M-Cache-3_ 40-GHz%29

  • 19. Re: iMac 27" runs VERY hot - too hot to touch.
    Cali4D Level 1 Level 1 (0 points)

    I have the 27" iMac and I am a 3D motion graphics artist so I am constantly doing very intensive 3D renders for days on end, and at the highest it's ever been is about 150 so I would defiantly get that looked at. And do you know if running bootcamp still controls the fan speed because on windows 7 my iMac has been getting quite hot.

  • 20. Re: iMac 27" runs VERY hot - too hot to touch.
    RRFS Level 5 Level 5 (4,430 points)

    Have any of you considered increasing the base or idle speed of your internal fans?


    here is a link for just such an app:




    Hope this helps.

  • 21. Re: iMac 27" runs VERY hot - too hot to touch.
    Tio Paulo Level 1 Level 1 (0 points)


    During the first year my imac 27 worked beautifully.

    For reasons of vacation, he got 20 days off.

    When I returned, I noticed immediately that it was extremely hot in the back, far beyond the normal.

    Today he is dead, even league.

    A one year warranty is over.

    Whereas it is not a cheap machine as an ordinary PC, ask colleagues if there is any historical Apple replace this equipment at no cost due to existing accounts?

    One response I thank colleagues.

    Paul Vidal from Brazil.

  • 22. Re: iMac 27" runs VERY hot - too hot to touch.
    rkaufmann87 Level 8 Level 8 (42,145 points)

    If you bought AppleCare then your machine will be fixed at no charge. However if you did not you are pretty much on your own.

  • 23. Re: iMac 27" runs VERY hot - too hot to touch.
    RonaldMHofmann Level 2 Level 2 (160 points)


    I have the same problem on my iMac27 espacially when running software to convert movies to mp4.


    To verify temperatures I also use iStat Pro. But I found something more powerful.

    Temperaturmonitor.app by Marcel Bresing which displays more detailed temperature distribution in your Mac:


    Bildschirmfoto 2012-12-15 um 01.51.53.png

    And I´m also using a tool (in case of emergeny ) to adjust fanspeed.

    smcfancontrol_2_4: http://www.macupdate.com/app/mac/23049/smcfancontrol


    Hope this helps.


    Greetings from Switzerland, Ronald Hofmann


  • 24. Re: iMac 27" runs VERY hot - too hot to touch.
    Sasparilla256 Level 1 Level 1 (45 points)

    Just have to mention, have a late 2011 iMac 27', it gets hot of course - but I never noticed it like today.  Because of the heat concerns (and one graphic card replacement on it) I reluctantly decided to replace it and sell on eBay while AppleCare was still in place (guessing the graphics card cooked itself and would do so again after AppleCare is gone).


    So today I brought home its replacement, hooked the two up via wired connections on AirPort (so 1Gbps network speeds) and had it transfer data (data migration assistant) to the new machine (about 250GB of data over a little less than hour) and it was so hot I could not believe it.  I kept both machines on task by constantly moving the mice (kept the screens on but also kept the transfer time estimate cut in half from what it was if the displays went off - guessing it kept the CPU's on one of them from going to a lower power state).  Guess the data migration assistant (Applications/Utilities/) really heats it up when its running.  Anyone who wants a reproducable way to crank the heat on their 2011 27' iMac look no further.


    The new iMac was barely warm around the center with no discernable temp increases out to the sides, bottom or top.  Secondary heat sink on the original 27' was showing 77C 4 minutes after the data transfer process was done - meaning it was probably above 80C during the process.  Coming from a gamer background on PC's I always ran my fans to keep temps below 70c on my video cards to ensure longevity.


    It's a shame such a beautiful machine gets so hot...as I want that DVD...but whatever.

1 2 Previous Next