External heat-sink for iMac?

Note: don't do this if you have one of the latest iMacs.

Also

http://www.eidac.de/?p=243

Not sure if such a thing exists. You should take it in for a free diagnostic in case the fans need replacing.

My iMac gets hot in the same place from time to time. Could be due to the physical location of certain heavily used components. If it is not a consistent problem I would just keep it under observation. If it is all the time, Klaus1's reply is the appropriate route.

it gets hot because it's where the cpu and gpu are located and the back of the case is used as a heatsink on imacs

Yes. That's what I had in mind when I posted earlier. You've identified the probable culprits 🙂

Hamper wrote:

Some GitHub software makes me a little nervous, but I wonder, if you have an experience with this software, can the fans be operated on the fly or is it a reboot-to-set sort of affair?

like the fan idea, is it your own, does it work?

Thanks.

smc Fan isn't from GitHub. I've been using it for years at a number of different presets. I would recommend, in general, not going higher than +4 or 500 rpms. Use the minimum rpms to keep the temps reasonable. Get Temperature Monitor to see the temps.

Don't understand the second question, is it my own? What difference does that make? Sure it helps.

Before resorting to the addition of custom fins, consider some more basic issues. First, if your fans are not running fast--at the default sped, they are close to silent except in the quitest room or office--your iMac is probably normal. The fans are thermostatically controlled; if temps start to climb, the fans will ramp up to handle it. If temps get too close to the danger point and the fans can't handle it, the computer does a safety shudown.

Next find out if your temps are a problem. What can "feel hot" to you is probably well within the computer's design specs so guessing doesn't help. I use Bresink's Temperature Monitor. It puts temps measured at the sensors in your menubar. Here is what my Mid 2010 27-inch iMac (2.93ghz quad core and big video hardware) is doing now after checking the Apple forums for about an hour:

Those are normal for my computer and workflow.

This Apple article:

Runaway applications can shorten battery runtime, affect performance, and increase heat and fan activity

can help you see if some roque software process is abnormally elevating temps.

Sure, the OP should post back with the temps, preferably in Celsius, or both C and F.

My take on what you wrote is that many people* feel that Apple is more interested in quiet fans (for marketing purposes) than in protecting the hardware, and although the fans will ramp up accordingly, they won't do that quickly enough or until they get to hardware killing temps (that is, hardware killing over the long haul.)

*many people includes an Apple bench tech I have spoken to in the past who was dealing all the time with hardware failure disasters.

WZZZ wrote:

Note: don't do this if you have one of the latest iMacs.

???

Why not?

I can't go and look at one easily--the next time I'm at Best Buy or some place like that I will--but I told someone here a few weeks ago to use the fan at the back (posted the same pic) and he said it was making things worse. I'm not sure, but from what he said it seemed to be interfering with the fan exhaust. It would do that on mine if it's aimed directly at the upper exhaust slot--that's why I usually tell people to place the fan low and aim it upwards (doesn't look like that in the pic, but it is), but he seemed to be saying that he didn't have that top slot on his. Some other exhaust arrangement maybe. Instead of an intake behind the stand, that's where the exhaust is, and that's where the air flow from the fan was hitting?

Maybe you know and can clarify?

That's quite happy. Continue to use until your touch suggests the case is up to the temps you noticed before, then recheck with the utility.