2012 iMac ventilation

Discussion in 'iMac' started by Gabichon, Oct 23, 2012.

  1. macrumors member

    Joined:
    Aug 27, 2011
    Location:
    Canada
    #1
    Hello

    The 2012 iMac is nice looking, has a good CPU, a decent GPU, okay.
    What about cooling down all that stuff? I only see holes on the bottom of the machine.. is it just me? There should be holes at the top too for good ventilation?

    If that's not the case then I doubt that machine will run cool :/
     
  2. macrumors 6502

    28Gauge

    Joined:
    Sep 4, 2011
    #2
    It is curious that the vents are on the bottom since heat rises.
     
  3. macrumors 6502

    Joined:
    Apr 30, 2012
    #3
  4. macrumors 6502

    28Gauge

    Joined:
    Sep 4, 2011
    #4
    You might be correct on the intakes.
     
  5. macrumors 6502

    El Awesome

    Joined:
    Jul 21, 2012
    Location:
    Zurich
    #5
    I was wondering too.
    I hope that there won't be MacBook-Pro-like fans that make jet-noise if you put some load on the machine.
     
  6. thread starter macrumors member

    Joined:
    Aug 27, 2011
    Location:
    Canada
    #6
    Maybe but on my mid-2011 it is an intake. Even if it would be an outtake it would be too small... Mmmh...
     
  7. macrumors member

    Joined:
    Jun 12, 2012
    Location:
    Brum, UK
    #7
    Didn't I hear him say that it only uses 50% of the power of its predecessor. Maybe runs cooler for that reason and ventilation is adequate. I guess Apple will have tested that aspect.
     
  8. thread starter macrumors member

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    Aug 27, 2011
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    Canada
    #8
    I'm not sure if I'm correct on this but I think they said 50% less energy when idle.
     
  9. macrumors member

    Joined:
    Jun 12, 2012
    Location:
    Brum, UK
    #9
    Yes, that could be right. Can't be bothered to re-run the presentation again to get the definitive answer.
     
  10. macrumors 68030

    Mr. McMac

    Joined:
    Dec 21, 2009
    Location:
    Long Island, NY
    #10
    Apple's cooling has never been state of the art. I wouldn't be surprised if there are reported cooling issues in the near future
     
  11. macrumors 68000

    Joined:
    Jul 30, 2012
    #11
    On the bottom are both intakes and outlets. And Ivy is baked on 22nm instead of 32nm, so that means half the heat at the same performance. They probably dropped the max brightness a bit, so that cuts the heat production by half.
     
  12. thread starter macrumors member

    Joined:
    Aug 27, 2011
    Location:
    Canada
    #12
    Well, on my mid 2011 the ventilation is pretty good :) (I use smcfancontrol)
    But I think that it'll be a problem on the 2012 model.

    ----------

    Where did you get that information? (that the bottom holes are both intakes and outlets)
     
  13. macrumors member

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    Jun 12, 2012
    Location:
    Brum, UK
    #13
    I suppose it depends on whether you live in Alaska or Nevada. Lol
     
  14. macrumors newbie

    Joined:
    Apr 27, 2008
    Location:
    Montreal, Canada
    #14
    Good find. I guess these take hot air from the processor out of the machine.
    Looking at the inside they showed and giving the fans I guess air flows in and out at the bottom.
    [​IMG]
     
  15. macrumors 68020

    Joined:
    Sep 14, 2012
    #15
    I only see one fan.

    For some reason it's *above* the heatsink and rear vent. I don't know what the idea is there. Suck cool air in from the bottom, blow hot air at it from the top, and see which direction wins? And hope that some goes sideways out the vent?
     
  16. macrumors 68040

    Joined:
    Feb 6, 2009
    #16
    It's an exhaust fan that probably has an air guide to the vents in the back.

    Looks to me like cool air will draft in at the bottom and hot air will get blown out the vent in the back, right near the CPU/GPU which is where you need to get rid of that heat.

    Edit: If you look carefully you can see a heat pipe on the logic board. It goes from the GPU on the left to the CPU in the center, and then probably to a heatsink that spans across those back vents. The fan is blowing air from inside the case through that heatsink and out the back of the case.
     
  17. macrumors member

    Joined:
    Sep 24, 2012
    Location:
    Tucson, AZ
    #17
    Heating and Cooling

    I’ve been looking at the heating angle. The new CPU is cooler but it’s the GPU that puts out the most heat, and the new one puts out more. But the heat news is not all bad. Just below the pedestal mount there’s a square grill to let the air flow out. There are air inlets at the bottom. The CPU fan looks to exit near the vent. The GPU fan is concealed; the unit is slightly above the top of the vent line, to the left looking with the screen removed. The HHD is to the right, a bit farther up. Its fan is not obvious. This presents balanced heat-sources: left, center, and right, tending to concentrate about half way up. The fact that the vent is square suggests to me that air flow is more complex than in my old iMac (more below).

    The fans do not draw air in through the bottom in an important way, but mostly create local circulation patterns. The heat of operation creates rising convection currents, drawing air in at the bottom. The expanding heated air creates a slight pressure rise with a flow out of the vent as a result. The fact that the vents are not along the top, as in my 2006 iMac, is at first glance surprising. In my iMac convection draws like a chimney. But the rear of the new model bulges in the middle, slightly farther out than the 2011 iMac. I think this creates a secondary convection flow from each side tending toward the center. Hot air accumulating at the top would contribute to the heating of the aluminum back generally (which cools by radiation and enhances the convection flow). Now Apple could put the vents on the back anywhere they chose. I think that they chose to maximize the cooling effect when they put them where they did. And I think a good deal of the room for the thinness is created by the new mounting of the display. I would guess that volumetrically the space behind the screens is comparable in the two models.
     
  18. macrumors 6502a

    djrod

    Joined:
    Sep 16, 2008
    Location:
    Madrid - Spain
    #18
    Kinda

    [​IMG]

    :D
     
  19. macrumors 6502a

    djrod

    Joined:
    Sep 16, 2008
    Location:
    Madrid - Spain
    #19
    this is where the heat leaves the machine:
     

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  20. macrumors 6502

    Joined:
    Apr 30, 2012
    #20
    I find it odd how some people seem to believe that Apple actually did not test these new iMacs, for all we know they could be cooler than previous generations! Heat dissipation is not a linear curve nor as simple as just adding more fans and vents. Looking forward to the reviews on this 'issue'! :)
     
  21. macrumors newbie

    Joined:
    Oct 24, 2012
    #21
    I am also worried about the ability of this new iMac to dissipate all the heat in the top-tier configuration.

    Let's say maxed GPU running heavy load, maxed processor at max turbo boost and intense SSD/HDD use... I know Apple engineers are clever but such a thin machine and so much heat... It makes me wonder how in hell this is gonna work...

    Anyone thinking of buying the top configuration and maybe waiting a bit longer to see if there are really any problems?
     
  22. macrumors 6502

    Joined:
    Apr 30, 2012
    #22
    Yep!
     
  23. macrumors 604

    theSeb

    Joined:
    Aug 10, 2010
    Location:
    Poole, England
    #23
    Their previous history when it comes to heat, iMacs and MBPs suggest that testing has not been very thorough.
     
  24. macrumors 6502

    Joined:
    Feb 28, 2012
    Location:
    UK
    #24
    Well, the world is just full of people who are more expert in heat generation and dissipation than Apple.
     
  25. macrumors 604

    theSeb

    Joined:
    Aug 10, 2010
    Location:
    Poole, England
    #25
    Posts like this are really helpful. It does not take a genius to realise when something is running too hot, if one is looking at the correct gauges. You don't need to sit here and apologise for all of Apple's engineering/design mistakes.
     

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