iMac 5k i7 cpu hits 100 °C regularly

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Level 1

7 points

iMac 5k i7 cpu hits 100 °C regularly

I recently bought the 5k 27" i7 iMac. When the cpu is idle it stays in the low 30s, when under moderate load (HD movies, internet, Photoshop etc) it doesn't really get over 50 °C, but when I use it to render stills/animations in Cinema 4D (or After Effects) and all 8 threads are being utilized the temperature stays almost constantly at 95 °C and regularly peaks at 100 °C! At this point the fan is louder than my vacuum cleaner, the frequency drops but the temperature never does. I did a test render for about an hour and the fan never managed to cool down the cpu under 90 °C, even if the frequency dropped from 4 GHz to about 3.8. I used Macs Fan Control and Intel's Power Gadget to monitor what is going on and got the same readings.

I don't think there is anything wrong with the cpu as it cools down to 45 °C in a matter of seconds after I stop rendering. The fault is (I guess) in the iMac's cooling system, since it uses the same heat sink for both the cpu and gpu (which by the way also gets over 90 °C after a few minutes of doing virtually nothing in Civilization V), and has to cool them both down, and the power supply, and the rest of the components all squeezed in a space smaller than some laptops have with only one fan.

My question is: how worried should I be? I don't think it is either normal or acceptable for the cpu to be at such high temperatures for longer periods of time. I don't do rendering every day, but I will do at least full 48 hours of rendering per month and having the cpu hitting the 100 °C mark every few seconds really doesn't sound right to me. Or am I just over reacting and it is perfectly normal for the i7 to operate in the 90+ range all the time?

iMac with Retina 5K display, OS X El Capitan (10.11.4)

Posted on Apr 11, 2016 9:27 AM

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Answer 1

MichelPM

Level 10

81,525 points

Apr 11, 2016 2:35 PM in response to Versagious

If you find out that these newer iMac models do run hotter, things you can do is run a software fan control with your iMac.

You can manually regulate the iMac's internal fan/s.

Apple is more concerned about thin design and quiet operation than worrying about prolonging the operational life of their computers.

I have been convinced for a long time that Apple, from the time of these new aluminum clad iMacs, has purposely changed the way they design and build their computers, now, to only last 5-6 years if you run them the way Apple wants you to run them.

Heat is enemy of all micro/nano electronic technology.

Run a small tabletop fan and let it blow cooler air from behind on the back of your iMac to help keep it running cooler, also.

I do this with my two iMacs to keep them running cooler to prolong component life.

I want my Macs to run as cool as possible.

I can't afford to purchase a new Mac every 5-6 years.

Good Luck!

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Answer 2

imac27i7

Level 1

4 points

Mar 24, 2017 8:29 AM in response to Versagious

hello

1 month ago i bought my new 27" imac like your (cpu:i7 4.0ghz + gpu: 4gb AMD Radeon R9 M395X...). I bought it because i work a lot with photoshop, indesign and in addition to this i started to "learn" cinema 4d... So when i start some rendering process (of few minutes), each cpu's core reach temperature of 98/100° not less than 96° for all the rendering process. So i have your same problem!!! How much time it will resist??? I don't think your is a isolated case becouse my imac do the same. Can you please tell me how did you resolve? Thanks

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Answer 3

Versagious Author

Level 1

7 points

Oct 28, 2017 4:27 PM in response to imac27i7

Hey, it's been over 6 months since your post (and it's probably too late), but i never really resolved the issue. The cpu still gets hot enough to boil water whenever I do video or cgi rendering - or anything that uses full cpu power. The rest of the time everything works fine. I never took the iMac back to the store to have it checked, they said they will have to send it to Vienna (their repair shop location) and the whole thing could take up to 3-4 weeks, and I never found a month of time to spare. As Apple announced the iMac Pro with two bigger fans 😉😉 I think there is nothing one can do with the i7 iMac, its just not really aimed at the "pro" market.

My solution is to render at night when I am out of the office, I still have a year and a half of Apple care left and if the cpu melts trough the aluminium, well, I guess I get a new iMac! I will sell it a few months before the Apple care expires though, I don't expect it to last 9 years as my old iMac did. I have a Macbook air and its all I need for internet and answering mails, as for work ... as BSD guru suggested I will probably build a hackintosh. I haven't tinkered with a PC in like 15 years and it actually sounds quite fun to do that again! The new iMac Pro will be just too expensive and frankly I don't trust the current iPhone focused Apple to build a proper machine. It's a shame, since it was graphic designers and people involved in desktop publishing that were the only ones buying their products when they were one step from becoming a footnote in history.

Anyway, not to make this into and old man rant: if anyone else is having this problem - post your cpu temperature madness, who knows, it might help someone make a more informed decision before buying the i7 5k iMac. Also if there is a solution to this problem, please post it - I would love to be wrong about the iMac, and will wholeheartedly apologise to the almighty corporation.

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Answer 4

theratter

Level 4

3,961 points

Apr 11, 2016 9:37 AM in response to Versagious

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

Be sure to check that none of your third-party apps in use are in a runaway state. However, those temps are not uncommon for any machine doing the same chores as yours. If the processors overheat then they will in turn cause the machine to shut down.

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Answer 5

Versagious Author

Level 1

7 points

Apr 11, 2016 9:55 AM in response to theratter

Yes I checked Activity monitor and there are no runaway apps. Apart from the Adobe Suite and Cinema I have almost nothing extra installed on the iMac. If I do nothing in Cinema 4D it uses like 0.3% of the processor.

I can't however accept that these are normal temperatures in any form of use. The old iMac that still runs great (but slow, it is 8 years old) never got over 70 °C and the fan barely ever made an audible sound. I don't think the machine will shut down, it is not malfunctioning - the processor will and does shut down, or better yet drops its operating frequency from 4.0 GHz because it hits its maximum operating temperature of 100 °C. Besides, is it really normal to buy a premium machine and then listen to the noise of the fan constantly at 2850 RPMs?

Perhaps I should rephrase my question: why is Apple selling the i7 processors and the M395X graphic cards (for extra 600 € I might add) if they generate too much heat for the iMac cooling system?

Is there a technician out there that might advise if there is any way to cool down the cpu without loosing any computing power in the existing iMac?

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Answer 6

MichelPM

Level 10

81,525 points

Apr 11, 2016 2:15 PM in response to Versagious

None of this sounds right to me for a new iMac.

A New iMac shouldn't be running this hot!

If you have had this iMac for less than 14 days, backup any new data you have on this new iMac, bring in your entire iMac system in the box, into an Apple Store, have them plug this in and show/demonstrate to them the issues you are having and see if they can diagnose the issue.

If the diagnosis isn't to your satisfaction, you can return this iMac for a full refund (wipe the drive of all your data and restore the iMac to its factory state, if still in the Apple Store, have a Apple employee or Genius help you with this) and then re-order/re-purchase another new iMac with everything you ordered the first time, and see if the same issue exists or to confirm that the first iMac you purchased was defective is some way the couldn't be diagnosed.

Good Luck!

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Answer 7

Versagious Author

Level 1

7 points

Apr 11, 2016 2:24 PM in response to MichelPM

Thanks MichelPM, I've had it for 19 days now 🙂 and there are no official Apple stores where I live, but the store where I bought it from (a premium reseller, whatever that means) already said they will do what you suggested if decide so. I did wait 3 weeks for this one though, so it's a lot of hassle.

I guess what I would like to know at this point is: if any other owner of 27" 5k i7 iMac with M395X graphic card has the same problem when they work on something that uses all the computing power that the processor has or is it just me? I'm still worried that this is a general problem and a new iMac with the same configuration will behave exactly the same.

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Answer 8

Versagious Author

Level 1

7 points

Apr 11, 2016 2:53 PM in response to MichelPM

I did put a fan at the back of the iMac 😀 but it didn't help. I also manually set the the fan to max 2850 RPMs, but it's so loud and didn't help either. I don't know, maybe they are really built to fail, I still prefer the saying ****-up before conspiracy, meaning Apple just didn't design the iMac with such heat generating components in mind.

I do rely on Apple to make something that works for a long time though. My 13 year old PowerPC still works and I used it as a file server until not long ago! That's why I would like to know what is going on with this iMac. I did consider buying a Mac Pro, maybe it would be better suited to my needs, but it really is quite expensive and this iMac is all I need for my work.

So, anyone out there with the same problems? Run some renders on your i7 iMacs, push them to the limits, that's why you payed the extra $$$ for!

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Answer 9

MichelPM

Level 10

81,525 points

Apr 11, 2016 7:36 PM in response to Versagious

There is sonething definitely wrong with this iMac.

You shouldn't be running the iMac's internal fans at 2800-2900 RPMs.

This is "Ludricrous Speed!" ( with all due respect to Mel Brooks).

You should only be running your iMacs fans at or below 2000 RPMs or so.

Bring it back in to your Apple Authorised seller.

If they cannot find the issues for the high heat, if they will take back for a full refund and once someone here can vouch for whether the high end iMacs have a pronounced heat issue., you can decide to try purchasing another one on the chance that the first iMac you purchased was a defective unit.

Good Luck!

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Answer 10

Versagious Author

Level 1

7 points

Apr 12, 2016 10:10 AM in response to Versagious

Well, I talked to someone at Apple Support over the phone, he was very nice but after we did the usual reset stuff (which I knew wouldn’t help and didn’t), he sort of confessed people usually call him about lost passwords and iTunes and this was a bit over his head. He did say the temperatures are too high and I should take it to the store to have it checked.

I also contacted Intel, the answer I got from their Discussion Support was (quote):

“Apple has requested that all questions regarding Apple systems and software be addressed directly with Apple support.”

and their Customer support sent me this (quote):

“When the BIOS option are set as default and the CPU is properly cooled, the i7-6700K should not overheat past 64C, as per Tcase figure. However, being this an Intel CPU mounted on a third-party board we cannot guarantee this figure. Your computer original equipment manufacturer (OEM) may have altered the features, incorporated customizations, or made other changes to the hardware provided.”

I am not completely sure what Tcase means, internet says it is the surface temperature of the processor and is usually 10 - 20 °C lower than the core temperature. In any case it is a sort of optimal temperature for the processor and even if my readings show core temperature (which I think they do) it shouldn’t exceed 85 °C - which it regularly does.

I’m taking my computer back to the store, though I don’t expect a major breakthrough. I will keep this discussion open and will post on how thing turns out, maybe it will help someone in the future.

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Answer 11

MichelPM

Level 10

81,525 points

Apr 12, 2016 3:19 PM in response to Versagious

I am pretty much a tech guy, and I have to agree with Apple.

A brand new Mac shouldn't be overheating.

You're the first person to post a question about heat issues with a brand new iMac.

So, MSO here, your heat issues is isolated defect to the iMac unit you received and is not a common, known issue for new iMac models.

So, I would bring back the whole kit and kaboodle and have an Apple/computer tech look this issue over and if there isn't a good resolution to fix or resolve the issue, return the iMac for a full refund.

Good Luck!

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Answer 12

BSD Guru

Level 1

14 points

Sep 30, 2016 8:56 AM in response to Versagious

The product is a disaster. The one fan simply isn't adequate to cool the system. I'm glad that I didn't get the i7, although the problem seems to be the LCD which runs way too hot. I've got TG Pro controlling the fan which is the only thing that keeps the system from shutting itself off as the system fan management doesnt work properly (or insists on running the fan at full tilt for no reason).

The iMac 5K is a great argument for blowing a day building a hackintosh.

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Answer 13

BSD Guru

Level 1

14 points

Oct 1, 2016 6:25 AM in response to MichelPM

What KIND of fan? Amazon link please

The air intake for the unit is on the bottom, so the ideal place to add a fan generally won't work. Do you just blow a cyclone fan at the back of the screen?

I've seen videos of guys that drilled holes in strategic places but I'm still under warranty and I'm not ready to go that route quote yet.

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Answer 14

MichelPM

Level 10

81,525 points

Oct 1, 2016 3:30 PM in response to BSD Guru

I use a small 7' inch diameter , 2-speed Vornado fan on the back of my iMac.

You do not a huge size external desktop fan to cool the back of your iMac.

Vornado, also has a 9 inch diameter fan with 3 speeds which I am thinking about switching formthe back of my iMac.

https://www.amazon.com/dp/B00D8NZ85I/ref=wl_it_dp_o_pC_nS_img?_encoding=UTF8&col id=20AIQPDUUWU9G&coliid=I2UFSK9YDS1DP6

It runs not too loud and does a good job of circulating the air and dispersing it from the back of my iMac.

Been using this for years on my 2009 iMac which gets incredibly hot, too!

You don't need to drill holes, just keep the back cool.

Aluminum is a good conductor of heat, but does a poor job of convecting the majority of that heat away from the iMac.

The heat issue used to be worse when Apple was making the iMac casing in earlier models in plastic, but those models had more than one fan AND Apple added more ventilation holes in the back casing of the iMac that allowed a lot more of the heat to more easily escape.

It, also, helps to identify on the backside and or top of the iMac where it gets the hottest and place the fan behind the iMac on the left or right side of the stand that gets the hottest.

On the older aluminum iMacs, looking at the iMac from the fronts, the left rear side and top is where my iMac gets the hottest.

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Answer 15

MichelPM

Level 10

81,525 points

Mar 24, 2017 9:41 AM in response to imac27i7

There is no real resolution.

If the heat from your iMac bothers you, as it does, myself, as I have already stated numerous times, run a small variable speed desktop fan on the back of your iMac.

In addition, install a software fan control to manually ramp the iMac's internal fans up and down, if needed, to compensate for what I feel is excessive internal heat.

If you use a software fan control, be careful not to ramp up the fan speeds too much causing the fans to act more like a vaccuum sucking in more outside dust, dirt, lint and to avoid premature burn out of the iMac's internal fan motors.

Been doing that for years!

Keeps all of the iMac's internal temperatures down and the back of iMac cool.

Fairly cheap solution.

A cooler running Mac will last longer as you won't be "slow roasting" internal components.

Good Luck to You!

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