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iMac Overheat Worry

J

jackmileshunt

macrumors member
Original poster
Jun 14, 2008
36
0
England
Hello, i am new to these forums,
I have been a mac user for some months now, and have not looked back, however, i have a concern, my imac gets very hot after prolonged use, so if i am in the middle of something, and i feel that its getting too hot, i shut down. As i am sure anybody can imagine, this is a pain, is this necessary, are there any known issues surrounding these imacs (late 2007 aluminium, came with tiger, upgraded to leopard).

Any assistance would be greatly appreciated, thankyou
:apple::apple::apple::apple:
 
well you can always turn on the air condition :D
it's always hotter on the toper surface of the imac and maybe thats because the fans are on the lower surface, sometimes my imac gets hot too, one time my imac is so hot, that my cd becomes very hot in a way i get worried about my cd's/dvd's
just download istate nano widget, it well give you the temperature of the cpu hard drive etc...
if you find it very high then i think you have fan problem :confused:.... i don't know the normal range but mine is always between 40-58c something like that
hope that your imac is ok
 
jackmileshunt said:
Hello, i am new to these forums,
I have been a mac user for some months now, and have not looked back, however, i have a concern, my imac gets very hot after prolonged use, so if i am in the middle of something, and i feel that its getting too hot, i shut down. As i am sure anybody can imagine, this is a pain, is this necessary, are there any known issues surrounding these imacs (late 2007 aluminium, came with tiger, upgraded to leopard).
Click to expand...

Exactly how are you making this determination of excessive heat? Are you just going by heat from touching the case or are you monitoring actual system temperatures? Obviously the latter will be a lot more informative.

The aluminum case of the current iMacs is particularly helpful in dispersing heat and I've not had any problems with mine. It gets pretty danged hot here in southern Japan in the summer too.

If you can get your actual temps (the iStat which alam recommended for you is an excellent choice) post what they are when you think it's running too hot.
 
Computers get hot. It's what they do.

There's no need to turn your machine off. You don't turn off your car because you think the engine is too warm!

The top of the aluminium iMac gets very hot because it's taking heat away from the inside of the computer (metal conducts heat). It's a very efficient design and your machine is not overheating.
 
Computers get hot but some have better cooling than others - I DO turn off my car if its running too warm ! And agreed you can't (shouldn't) go by feel alone.
 
Thanks

okay, thanks for all of your replies, i have just switched my machine on, so i will post temps later on when it gets hot, and thanks
 
Leon Kowalski said:
So, why does virtually every car in the world still have a temperature gauge?

...and why did Apple install so many temperature sensors?

LK
Click to expand...

Yeah... what he said!

I'm so tired of all these posts I read where people are like "well if your computer is 3000 degrees, it's because Apple designed it that way!"

False.
 
To all the people saying it gets to hot (by touch):

Don't you realize that this is what is meant to happen? It is an excellent design. Aluminum conducts heat, transferring it from the computer to the surroundings. That is why the aluminum is so hot; because it is doing its job very very well. If the case was cold, the material would be insulating the heat, keeping it inside the computer, which would be very bad.

To everyone: stop worrying.
 
sk8mash said:
To all the people saying it gets to hot (by touch):
Click to expand...

Let the poor kid actually come back and post some numbers. It *is* possible there's something wrong with his/her Mac that's causing it to get too hot. What's the point in jumping to conclusions when he/she promised to come back in a couple of hours with temperatures?
 
mkrishnan said:
Let the poor kid actually come back and post some numbers. It *is* possible there's something wrong with his/her Mac that's causing it to get too hot. What's the point in jumping to conclusions when he/she promised to come back in a couple of hours with temperatures?
Click to expand...

Im not directing it specifically to him. There are alot of threads about iMac heat. But it is very unlikely there is a faulty fan anyway! :)
 
sk8mash said:
Aluminum conducts heat, transferring it from the computer to the
surroundings. That is why the aluminum is so hot; because it is
doing its job very very well.
Click to expand...

A) The iMac is supposed to be air-cooled -- that's why it has three
fans inside. There is NO intimate contact between the CPU, GPU,
HDD, etc. and the aluminum bezel. As these photos clearly show,
the elaborate CPU/GPU heatpipe assembly is directly in the airflow
path of the large fan in the lower left-hand corner -- and has NO
significant path for thermal conduction to the case. Same deal with
the HDD: directly fan-cooled, with NO thermal bonding to the case.

B) If the case is hot, the stuff inside must be even hotter...

...it's called Physics 101,

LK
 
Leon Kowalski said:
A) The iMac is supposed to be air-cooled -- that's why it has three
fans inside. There is NO intimate contact between the CPU, GPU,
HDD, etc. and the aluminum bezel (see photos).

B) If the case is hot, the stuff inside must be even hotter...

...it's called Physics 101,

LK
Click to expand...

Im sorry, but thats just not true. Firstly there doesn't have to be contact between components and case for heat to be transfered. It will be transfered by convection and conduction to the aluminum case, which radiates the heat. The only way it could be hotter inside is if the aluminum is acting as an insulator, which it is not, or if heat is being produced faster than it is radiated. In any case, the aluminum is still acting as a conductor, dispersing the heat. This is the sole reason it feels hot. An insulator would feel cold to the touch.

...it's called Physics 101.
 
sk8mash said:
Firstly there doesn't have to be contact between components and case for heat to be transfered. It will be transfered by convection and conduction to the aluminum case, which radiates the heat.
Click to expand...

Firstly, contact is required for conduction. (Got dictionary?)

Secondly, air is a crappy heat-transfer medium for convection.
(That's why it's used as an insulator in double-glazed windows.)

The only way it could be hotter inside is if the aluminum is acting as an
insulator, which it is not, or if heat is being produced faster than it is
radiated.
Click to expand...

...uh, lemme guess ...you're not an engineer or a physics major?

LK
 
To the O.P. I felt the same way about my mac mini, I live with zero air conditioning so it is a very real issue. I downloaded smcfancontrol and not only does it display temperature it allows you to control fan speed manually. So if things start getting hotter than you like you can crank it up until it cools off then go back to default. Just a recommendation.
Oh and heres the link for the download: http://homepage.mac.com/holtmann/eidac/software/smcfancontrol2/index.html
 
Could hurt someone

I have a g5 and just got an iMac today...the outside of the iMac case reached a temp of between 140-150 degrees F...65.55 C...hot enough to burn a child if they touch it. The temp of the components is fine according to the istat but a game did freeze up today and I think it was because it got too hot. When I removed the disk I dropped it because it was too hot to touch.

My husband is getting his thermal camera from work to take a more accurate reading. Even though some say it is supposed to get hot, why would you want to accept that if it could actually burn someone? Children have lower tolerances. When you have young children you are supposed to keep your water heater set to 120 degrees F (48.88 C) so that they don't accidentally get scalded when using water so unless you don't have little kids or plan on banning them from using the computer it's too hot at 140-150 degrees F.
 
Leon Kowalski said:
Firstly, contact is required for conduction. (Got dictionary?)

Secondly, air is a crappy heat-transfer medium for convection.
(That's why it's used as an insulator in double-glazed windows.)



...uh, lemme guess ...you're not an engineer or a physics major?

LK
Click to expand...

Interesting theory that air is crappy for heat transfer. I may not be an engineer or a physics major but I do know that when I use my hand held blow dryer on my hair it gets pretty darn hot. I would pretty much guarantee that if I aimed the same blow dryer at a piece of aluminum for a period of time it would get hot too. I guess my hair dryer is an exception to your theory?
 
LJphoto said:
I may not be an engineer or a physics major but I do know that when I use
my hand held blow dryer on my hair it gets pretty darn hot.
Click to expand...

Maybe that's why they call it a BLOW dryer? Now, turn off the blower and see
how hot your hair gets with only convection from the 1.5 kW heating element.

"Few things are harder to put up with than the annoyance of a good example."
-- Mark Twain

.
 
Leon Kowalski said:
Maybe that's why they call it a BLOW dryer? Now, turn off the blower and see
how hot your hair gets with only convection from the 1.5 kW heating element.

"Few things are harder to put up with than the annoyance of a good example."
-- Mark Twain

.
Click to expand...

True. Correct me if I am wrong but aren't there fans inside the iMac? And do the fans not also blow?
 
What I really want to know is how on earth it can be considered normal and acceptable for the aluminum exterior case of my iMac to reach a temp of 150 degrees F, enough to burn a toddler's hand even when the components inside are at "normal" operating temps?

Oh and could the heat be the cause of the computer locking up at least 3 times when shutting it down? It just sat there with the gear spinner spinning for over 10 minutes when I finally just hit the power button...never had this with my G5.

I have a G5 Power PC which has never in the 3 years I've had it locked up. The iMac is new to me today and I am already very frustrated with it. First a game froze and the disk wouldn't eject. When I finally got it to eject it burned my hand so bad that I dropped it. I ran a diagnostic utility as per AppleCare and everything came back "normal". Istat says the fans are running and that the internal temps are fine but the case is too hot to touch and I would be afraid that a child would be hurt. I'm also a bit afraid of it catching fire. My husband actually had a monitor catch fire while he was using it. Smoke suddenly started billowing out of it and when we looked at the back of the case it was melted. So we are a bit scared to walk away from the iMac for that reason with it being so darn hot.

I got this one for my middle son who is college bound and now I have fears of him using it in a dorm. I'm afraid he will have papers too close and it will catch fire if it overheats.
 
Similar Problem - Any Suggestions?

Sorry to interrupt the interesting physics discussion on heat transfer, and also, I don't want to hi-jack the original posters thread.

I have a 3.06Ghz 24" Aluminum Imac. I thought it was running a little too hot, so I installed Fan Control. I didn't like it, so I removed it and tried SMCfancontrol, latest version. I noticed that after installing, the fans did not speed up under heavy processor load, even if the temperatures rose significantly. So I removed SMCfancontrol, shut down, did an SMC reset and a PRAM reset on startup.

Now, under 100% processor load, CPU A temp reaches 75 degrees Celsius, and the fans do not speed up past default idle speeds 1200rom CPU fan, 1200rpm HDD fan, 700rpm ODD fan, even when the CPU stays this hot for an extended period of time.

Questions:

1.)At what temperature should the fan speed increase? I could not find this info anywhere!

2.) Is it possible that either Fan Control or SMCfancontrol altered firmware settings, and if so, is there a way to restore the firmware settings?

3.) What is the maximum operating temperature of the Penrynn chips used in these iMacs?

I would really appreciate it if anyone has any information or suggestions here!

Thanks,

Sonic
 
LJphoto said:
Correct me if I am wrong but aren't there fans inside the iMac?
And do the fans not also blow?
Click to expand...

Congratulations! You're slowly catching on.

Leon Kowalski said:
The iMac is supposed to be air-cooled -- that's why it has three fans inside.
Click to expand...

The iMac is designed to be AIR COOLED by direct-contact heat transfer
(conduction!) from the internal components to the fan-driven moving
air stream -- then out the rear vent. If the case is more than a few
degrees above room temperature, the cooling system is busted.

LK
 
Leon Kowalski said:
Congratulations! You're slowly catching on.



The iMac is designed to be AIR COOLED by direct-contact heat transfer
(conduction!) from the internal components to the fan-driven moving
air stream -- then out the rear vent. If the case is more than a few
degrees above room temperature, the cooling system is busted.

LK
Click to expand...

I think we've been on the same page...the hot air is transferring the heat to the case since there doesn't seem to be enough outlets for the hot air in the iMac case. The fact that the measured case temp being 140-150 degrees on 3 different thermometers that I attached to the case seem to bear that out.

My Power PC G5 has 7 fans and the case being so open and so much larger allows significantly more air flow even though the components actually are running hotter than the iMac the G5 case is as cool as can be...this iMac is scary hot...I actually mentioned it to AppleCare that I burned my hand on the disk when I called about it locking up and they were alarmed enough to open a case. AppleCare had me run a Utility test of some sort from the install disk that took over 30 minutes and it all came back normal...the fans are running at normal RPM's...the component temps are within the expected range and are "normal" according to iStat. They are definitely leading me to believe this is not at all normal. They are "looking into it" and said they will probably have me return it to the store it just shouldn't be that hot. My husband uses a FLIR infrared camera to inspect power lines for hot spots and he is going to bring it home to take a more accurate reading of the temp of the case. It will also document the problem for us.

We are very alarmed because none of the iMacs in the store were hot, and believe me we checked. That was one of the first things we did. The cases on the ones in the store were very comfortable to the touch. So anyone who says that you cannot judge it by the feel of the case all I can say is that's fine unless you want to risk getting burned. I reached over the top of the thing and the inside of my arm touched it and it left a shiny red mark for several minutes. It's no longer red but there is a shiny line on the inside of my forearm. If it was a young toddler it might have been worse.

I have hands like leather and they are not at all sensitive to heat and the case gets too hot for even me to touch for any length of time.
 
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