Is my iMac running too hot?

Hi,

Temps around that level are pretty good. If it gets too warm it'll increase the fan speed, and as a safety measure would eventually turn off if it got too hot, but it's safe and normal for temperatures to reach 75+ degrees Celcius.

Honestly you shouldn't have to, it will automatically shut down in the event that it overheats ( as far as i am aware). It would be personal preference to shut it down at 80, i dont like my machines running that hot but that is just me.

Glad to help.

james_mcq wrote:

Hi,

Temps around that level are pretty good. If it gets too warm it'll increase the fan speed, and as a safety measure would eventually turn off if it got too hot, but it's safe and normal for temperatures to reach 75+ degrees Celcius.

NO. That is very poor advice. Safe and normal at 75+ is dangerous territory for most hardware. And telling someone it will shut down if it gets too hot is like telling someone not to worry, they'll pass out from heat exhaustion if they get too hot. I don't like to see the the CPU climb above middle 50's to 60. And I like to keep the drive below 50. I prefer to keep temps quite a bit lower, in fact. Here are some temps from a reasonably warm day here. Using smcFan Control on second lowest setting I've established.

It is well known that Apple has the fans set to speed up only after things get too hot. Heat allowed like that, long term, can kill hardware.

@ red: Get smcFanControl. Post back if you want some instructions on using. Running a small fan at the aluminum back will also help to remove heat.

WZZZ wrote:

<snip>

It is well known that Apple has the fans set to speed up only after things get too hot.

@WZZZ

I'm wondering why Apple would have got things so wrong and create overheating. What's the source of this information?

Also, in the graphic, what's the "Specified Upper Limit" of 100 degrees C?

You will find considerable disagreement on this, but many feel it has to do with Apple trying to appeal to people who want quiet fans. Quiet fans + very thin, slick looking design (with limited airflow) equals more computer sales. I don't think Apple cares much anymore about keeping computers going for more than three years (the time Applecare is up.) At five years, it becomes a legacy product. (My iMac G3 slot, no fans, but much more room inside, is still going. But I owe some of that longevity to running a fan over the exhaust at the top to keep it cool.)

The PRAM battery on my 21.5, a readily available lithium button battery, which has a lifetime of around 5 years, is deeply buried. Something like 35+ steps to get to it. It keeps going even after you remove the logic board. Completely nuts! This is something, like the drive, which should be user replaceable. The iMacs are becoming more and more impossible to work on. It's just an obsolete appliance you throw away when it breaks. So who care if the heat, over time, gets it.

I'm not sure where the specified upper limit comes from. That is Marcel Bresink's Hardware Monitor. He reverse engineers a lot of stuff in his programs, but I think he gets that specification from Apple. I don't see him figuring that out on his own. Of course, 100C is insanely hot and probably just a theoretical number. I wouldn't use it to establish any guidelines for the CPU Temp.

Yes, but what is the source for your information about slow fan speeds and the temperature limits you quote?

John Kitchen wrote:

Yes, but what is the source for your information about slow fan speeds and the temperature limits you quote?

Mostly anecdotal from other users with years of experience, reports of hardware failures associated with high temps, other boards and an Apple bench tech. I didn't quote any exact temperature limits. If you want to believe that Apple engineers this properly, that's comletely up to you. As I said, you will find those who do. Not interested in debating this.

Suggest you read this about drive temps.

http://www.codinghorror.com/blog/2006/12/hard-drive-temperatures-be-afraid.html

Using smcFan: I have five settings, starting with the defaults, each in increments of about 15-20% up to near 2K. I try to run the fans as conservatively as possible. You don't want to burn up the fan motors. I mostly run a few hundred rpms above, or when things are getting hotter, at the second setting you see in my screenshot. (This will depend on what the defaults are for your Mac. If it's a 27" with bigger fan blades -- mine is a 21.5 -- the defaults will start out a bit lower than mine.)

The aluminum back acts as a huge heatsink. I run a 6" clip-on fan mounted to the wall behind the computer. It is aimed at the hottest part of the back, the upper left as you face the screen. And it is quite near, maybe 6" away. It helps to move the heat away.

That said, no amount of cooling or revving up the fans is going to help if the ambient is very hot, especially with high humidity. You're just blowing hot air around things, which has diminishing returns.

When things get too hot here, I just sleep the computer more often. Without sleeping the computer, you can keep things cooler by sleeping the display, which throws off a lot of heat. The fans keep running. You can set the display to sleep in five minutes or so. (SystemPreferences>Energy Saver.) Or directly with Control-Shift-Eject.

Note also that if you are doing something CPU intensive it is normal for the temp to climb. Applications which are graphics intensive will also boost the temps.

The CPU at 62C isn't in dangerous territory, but if you can get it down a bit, it can't hurt.

@WZZZ

Not sure why you would think I was looking for "a debate". You raised an issue which bothered me, and made me feel my iMac is at risk due to bad decisions by Apple, so I wanted to see supporting evidence.

My CPU temps are above 50C for most of the time, and if I get all cores really cranking, they get up to 90C for a while, so you got me worried and I want to be sure whether I should be worried or not.

This is not a debate, but a quest for knowledge!

Hi red33m

I going to have to side with WZZZ in these matters and add that heat kills.

I think that it is great that you are concerned, because the iMac's hardware can and will run hot when the ambient is up and when it is under a load.

While Temperature Monitor: Download offers a selected menu bar read out and better details, I personally use the iStat Pro, a Dashboard Widget by iSlayer to quickly check the various components within my iMac.

For the sake of argument,I have a Jan 2006 Intel iMac that I have kept in check for over 5½ years now by regularly vacuuming out the air intake ports and using SMCFanControl. With that, I never let my HD go over 50C, my CPU go over 60C, my GPU go over 70C and I'm betting that it will run for 5½ more.

Dennis