2012 iMac ventilation

Gabichon

macrumors member
Original poster
Aug 27, 2011
80
9
Canada
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 :/
 

28Gauge

macrumors 6502a
Sep 4, 2011
510
93
DFW
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 :/
It is curious that the vents are on the bottom since heat rises.
 
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El Awesome

macrumors 6502
Jul 21, 2012
471
0
Zurich
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.
 
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Dougie83

macrumors member
Jun 12, 2012
35
7
Brum, UK
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 :/
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.
 
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Gabichon

macrumors member
Original poster
Aug 27, 2011
80
9
Canada
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.
I'm not sure if I'm correct on this but I think they said 50% less energy when idle.
 
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blanka

macrumors 68000
Jul 30, 2012
1,549
3
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.
 
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Gabichon

macrumors member
Original poster
Aug 27, 2011
80
9
Canada
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
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.

----------

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

macrumors newbie
Apr 27, 2008
20
16
Montreal, Canada
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motrek

macrumors 68020
Sep 14, 2012
2,424
149
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.
Image
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?
 
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Stetrain

macrumors 68040
Feb 6, 2009
3,548
18
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?
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.
 
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Tucson Allen

macrumors member
Sep 24, 2012
44
0
Tucson, AZ
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.
 
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djrod

macrumors 65816
Sep 16, 2008
1,009
25
Madrid - Spain
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?
Kinda



:D
 
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Mister Bumbo

macrumors 6502
Apr 30, 2012
391
0
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'! :)
 
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Qutrit

macrumors newbie
Oct 24, 2012
11
0
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?
 
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theSeb

macrumors 604
Aug 10, 2010
6,963
91
Poole, England
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'! :)
Their previous history when it comes to heat, iMacs and MBPs suggest that testing has not been very thorough.
 
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JustMartin

macrumors 6502a
Feb 28, 2012
762
243
UK
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'! :)
Well, the world is just full of people who are more expert in heat generation and dissipation than Apple.
 
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theSeb

macrumors 604
Aug 10, 2010
6,963
91
Poole, England
Well, the world is just full of people who are more expert in heat generation and dissipation than Apple.
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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