Alarmingly High CPU Temperature on 2020 27" iMac

[jobinhosyntax]

Is this putting anyone else off ordering a 2020 iMac?

It just feels a bit dirty of Apple to release these chipsets in the current design, with only one, small fan.

 

[edib]

That video does NOT reflect the 2017 iMac's behavior at all. Not even close. Let me explain.

Disregarding the fact that he is running Cinebench Multicore, a maximum CPU load scenario that rarely ever (aka: practically never) occurs in the real world he's running that benchmark on the 95W 4.2 GHz Core i7 CPU that the iMac was never designed for. The iMac's cooling system was designed for 65 W CPUs, not 95 W CPUs. Part of why Apple is now switching to Apple Silicon is the fact that Intel was unable to produce low to medium power high-performance CPUs but instead simply started increasing thermal limits. Apple had no choice but to opt for high-performance high-power chips to satisfy the performance-hungry crowd of semi-professionals and professionals looking for the best bang for the back. Just for funs and giggles I ran the Cinebench R20 multi-core benchmark on my 2017 Core i5-7500 quad-core iMac running at 3.4 GHz with a Turbo Boost of 3.8 GHz. I had the fan set to Auto idling at 1,200 rpm, and that's exactly where it remained throughout the entire test. CPU temperatures peaked at slightly over 70 °C and even after more than four minutes of non-stop maximum load my fan was still pegged at 1,200 rpm. Now, with a 95 W CPU this is a very different story but that fact has been well-known since 2015.

I'm still busy working right now but I will create and upload a video to YouTube later tonight proving how long it will take for my 2017 iMac to start ramping up its fans at all, and what it actually takes to have them running full blast.

The i5 in the 2017 iMac at 65W TDP is a sweet spot. I never had an issue with the fan noise at 1200rpm on it. To put things in perspective I have returned one, same model, due to fusion drive noise.

I am already regretting selling the 2017 iMac. The new one with i7 arrives tomorrow, however based on what I am reading on this forum it will most likely go back. 125W/95W TDP/TPD-down is definitively too much for the outdated cooling system.

I would love to buy another iMac, however it seems like there aren’t any viable options at present. Maybe a Mac mini with the LG 5k display if I can still source one. Alternatively, Corsair One i165 (amazing form factor for a PC, performance with RTX2080Ti and cooling - silent at idle), however going back to Windows would be painful.

 

[wardie]

I remember reading exactly the same kinds of posts 3 years ago just when I ordered my 2017 i7 27” iMac. Jet engine noise and frying chips, allegedly. It’s really quiet normally in my home working environment and 95% of the time in use fans don’t spin up. It’s noisy when the fans go full tilt but that only happens when I run Lightroom batch jobs or gaming. Which I don’t do professionally for hours at a time. A workaround I found is to disable turbo boost, which really keeps the fan noise down even under full load, trade off only few % performance on that CPU.

But if you need a near-silent machine for sustained CPU/GPU intensive workloads, then an high end CPU iMac isn’t the answer. iMacPro or Mac Pro is. I also have a 2008 Mac Pro old cheese grater with the fantastic large fans at the front which made it really quiet even under load on the twin Xeon quads in it. Shows what you can do with physical space.

 

[edib]

I remember reading exactly the same kinds of posts 3 years ago just when I ordered my 2017 i7 27” iMac. Jet engine noise and frying chips, allegedly. It’s really quiet normally in my home working environment and 95% of the time in use fans don’t spin up. It’s noisy when the fans go full tilt but that only happens when I run Lightroom batch jobs or gaming. Which I don’t do professionally for hours at a time. A workaround I found is to disable turbo boost, which really keeps the fan noise down even under full load, trade off only few % performance on that CPU.

But if you need a near-silent machine for sustained CPU/GPU intensive workloads, then an high end CPU iMac isn’t the answer. iMacPro or Mac Pro is. I also have a 2008 Mac Pro old cheese grater with the fantastic large fans at the front which made it really quiet even under load on the twin Xeon quads in it. Shows what you can do with physical space.

It is all about the fan noise at idle (1200rpm) when doing during basic and non-intensive tasks - reading docs, composing emails, etc. All my previous iMacs (had most of them since 2009, always 27” top tier with the best GPU I could get) were very quiet.

Also, according to Apple tech specs the 2020 i7 model is quieter than the 2017 i5 at idle.

I don’t think anybody is expecting their iMacs to be quiet while gaming, mine (2017 i5) was almost as loud as a vacuum cleaner during my short gaming sessions.

 

[mj_]

As promised earlier today here's the video of me trying to get my iMac to run its fan at full speed. Spoiler alert: I've failed miserably. After 30 minutes of full CPU load on all four cores running Cinebench R20 (and four simultaneous instances of yes at the beginning) with an ambient indoor temperature of 78F/28C (this is Texas after all) my 2017 iMac's single fan topped out at just shy of 1,600 rpm. I guess you really need that 95 W i7 in order to get the fan up to full speed.

(Please excuse the poor audio quality, the only mic I've had available is my JBL headset's integrated microphone)

So much for "After 10-20s or so the fan ramps up to full speed" and "poorly designed cooling system". The fan was definitely very noticeable at 1,600 rpm but not really bothersome considering the long period of high load. That said I've stated multiple times in other threads that I usually run my iMac's fan at 950 rpm, which is as low as it will go, because 1,200 rpm is already annoying and I can't stand the noise it makes. I can definitely attest to the fact that the iMac's cooling system is perfectly adequate to cool a 65 W CPU in a comparatively quiet and perfectly acceptable manner, and that it usually remains at 950 rpm all day long with me running various office applications, several background VMs, and more simultaneously. Gaming might be a whole different story but since I use my iMac exclusively for work and not gaming I can't say anything about that load scenario.

 

[edib]

The new i5 (i5-10500) in the 2020 iMacs is also a 65W TDP CPU as per the Intel spec sheet. Number of reports in this forum suggest that the i5 iMacs are as loud as the i7 ones. It seems that the difference is that the 2017 i5 doesn’t go above 45W (in your test) as compared to the recent 2020 i5 which goes up to 80W in a similar test.

Intel® Core™ i5-10500 Processor (12M Cache, up to 4.50 GHz) - Product Specifications | Intel

Intel® Core™ i5-10500 Processor (12M Cache, up to 4.50 GHz) quick reference with specifications, features, and technologies.

ark.intel.com

 

[RAWvJPG]

@mj_ This fan behavior applies to the i7 2017 27" model only and it seems very likely that the current 2020 i5 behaves in the same way given its higher TDP and TIM. And yes, I still consider it poorly designed for two reasons: 1: It's not silent at idle despite other Macs showing it's possible, 2: I consider 2700 rpm totally unacceptable under load for a regular i5 or the older i7 7700K. These are not 130W TDP Xeon monsters but regular desktop CPUs.

Thanks for the effort of making the video. 1600 rpm is totally fine, but your video also suggests the iMac is designed to handle around 45W.

You should've seen my 21.5" i5 7400 iMac. Fan would always stay at 1200 rpm no matter what I did to it and that was completely silent. Also shows Intel's failure the past 5 years. TDP keeps going up and the pinnacle has been reached with Comet Lake.

 

[macbro08]

Is this putting anyone else off ordering a 2020 iMac?

It just feels a bit dirty of Apple to release these chipsets in the current design, with only one, small fan.

Yes - seems like people here are also slowly, but surely, starting to realise the shortcomings of the iMac 2020....

 

[edib]

@mj_ This fan behavior applies to the i7 2017 27" model only and it seems very likely that the current 2020 i5 behaves in the same way given its higher TDP and TIM. And yes, I still consider it poorly designed if it cannot handle a 91W CPU. We are talking desktop CPUs after all. Thanks for the effort of making the video. 1600 rpm is totally fine, but your video also suggests the iMac is designed to handle around 45W.

You should've seen my 21.5" i5 7400 iMac. Fan would always stay at 1200 rpm no matter what I did to it and that was completely silent. Also shows Intel's failure the past 5 years. TDP keeps going up and the pinnacle has been reached with Comet Lake.

mj_’s test was done on his 2017 Core i5-7500 not the i7.

 

[CooperBox]

There's some good info here. How does the above compare to the 2019 27" iMac19,1 in terms of temps and fan noise when running demanding tasks?

 

[1229175]

Is this putting anyone else off ordering a 2020 iMac?

It just feels a bit dirty of Apple to release these chipsets in the current design, with only one, small fan.

I'll be returning mine, if that helps with anyone's decision-making here.

I believe this iMac's design, originally from 2012, is completely inadequate for these current Intel processors. Apple should have redesigned iMac and its cooling system in 2017 when it became apparent that Intel was struggling to move beyond 14 nm.

 

[Fred Zed]

mid tier 2020 model here. No issues with heat or noise.

 

[1229175]

mid tier 2020 model here. No issues with heat or noise.

What is your CPU temperature at 100% load?

 

[mlykke]

What is your CPU temperature at 100% load?

Listen, unless you have a custom cooled PC then most CPUs will get close to 100 degress if it keeps running at 100% load. So instead of trying to force a worst case scenario why don't everybody calm down a bit and think about how it behaves in normal use. 99,99% of people will never see the CPU run at 100%. So unless you do heavy rendering or spend your entire day exporting 4k footage, then the temperature on max doesn't matter.

I've had multiple iMacs over the last 10 years and every single one has been dead quiet 99,9% of the time. Only when I did short heavy loads of rendering and encoding it would spin up. And yes, then it will be quite noticeable, but it's not like a wacuum cleaner next to your head. If you can't live with this for the 2-20 minutes a load like that usually takes, then the iMac is not for you and no version has ever been.

 

[CooperBox]

Is this putting anyone else off ordering a 2020 iMac?

It just feels a bit dirty of Apple to release these chipsets in the current design, with only one, small fan.

Well after some reflection it's not exactly inspiring me to get one, and I was thinking about it.
I was more than surprised to hear that there is only one fan, especially as my mid 2010 27" Imac 2.8GHz i5 has three, and after adding a Samsung SSD and more memory is still performing like a champ. Sure, those fans can and do collect a lot of debris as I noticed after 8 years of use, but never showed signs of overheating. Can't help wondering how the 2020 will perform after 8 years if never opened......

 

[CWallace]

The CPU is not the only hot part in an iMac. There is also the GPU and if one's workload is working both hard...

Also, Intel's TDP ratings no longer represent the top end of operating power. If the cooling supports it, for years now the Intel CPUs Apple use can pull two or three times that. So even though Apple does not overclock the CPUs, the fans are going to scale to maximum (2700RPM) to try and keep the CPU at full performance (at which point you can be sure it is pulling a fair bit more operating power than the listed TDP).

 

[1229175]

Listen, unless you have a custom cooled PC then most CPUs will get close to 100 degress if it keeps running at 100% load. So instead of trying to force a worst case scenario why don't everybody calm down a bit and think about how it behaves in normal use. 99,99% of people will never see the CPU run at 100%. So unless you do heavy rendering or spend your entire day exporting 4k footage, then the temperature on max doesn't matter.

I believe your perspective is entirely flawed. iMac can be configured from $1,800 to $8,800. A computer of that price should be able to operate at 100% CPU load without being within 0.3º C / 0.5º F of the processor's maximum operating temperature. Tjunction for this Intel chip is 100º C. Hitting 99.7º C under a one-minute stress test is a joke, in my opinion. A single fan for both the CPU and GPU is also a joke, in my opinion.

Everyone here is free to have their opinions on what an $1,800–$8,800 machine should be capable of, but accepting a 0.3º C / 0.5º F buffer to maximum temperature seems like a low standard to me.

 

[1229175]

Well after some reflection it's not exactly inspiring me to get one, and I was thinking about it.
I was more than surprised to hear that there is only one fan, especially as my mid 2010 27" Imac 2.8GHz i5 has three, and after adding a Samsung SSD and more memory is still performing like a champ. Sure, those fans can and do collect a lot of debris as I noticed after 8 years of use, but never showed signs of overheating. Can't help wondering how the 2020 will perform after 8 years if never opened......

I didn't realize there was only one fan before purchasing, as well. Here's the x-ray iFixit took during their tear-down.

Source: https://www.ifixit.com/News/43287/apples-last-dance-with-intel-imac-27-2020-teardown-with-x-rays

It looks like there's plenty of space for a second fan and I believe the cost for Apple to install one would have been minimal. I'm disappointed they left the design as-is from 2012.

 

[macbro08]

I believe your perspective is entirely flawed. iMac can be configured from $1,800 to $8,800. A computer of that price should be able to operate at 100% CPU load without being within 0.3º C / 0.5º F of the processor's maximum operating temperature. Tjunction for this Intel chip is 100º C. Hitting 99.7º C under a one-minute stress test is a joke, in my opinion. A single fan for both the CPU and GPU is also a joke, in my opinion.

Everyone here is free to have their opinions on what an $1,800–$8,800 machine should be capable of, but accepting a 0.3º C / 0.5º F buffer to maximum temperature seems like a low standard to me.

I agree with this sentiment. Considering the amount of resources Apple put into the overall design of the iMac, it seems odd they didn't spend a minimum of effort trying to optimise what has been known to be an issue for at least a years time now: Cooling the iMac

 

[mlykke]

I believe your perspective is entirely flawed. iMac can be configured from $1,800 to $8,800. A computer of that price should be able to operate at 100% CPU load without being within 0.3º C / 0.5º F of the processor's maximum operating temperature. Tjunction for this Intel chip is 100º C. Hitting 99.7º C under a one-minute stress test is a joke, in my opinion. A single fan for both the CPU and GPU is also a joke, in my opinion.

Everyone here is free to have their opinions on what an $1,800–$8,800 machine should be capable of, but accepting a 0.3º C / 0.5º F buffer to maximum temperature seems like a low standard to me.

As you said, we all have our opinions. But if you step away from the "it's a joke" hyperbole for a moment, what do you actually do on your computer 99% of the time? And does that activity cause all CPU cores to be constantly at 100% load?

 

[1229175]

As you said, we all have our opinions. But if you step away from the "it's a joke" hyperbole for a moment, what do you actually do on your computer 99% of the time? And does that activity cause all CPU cores to be constantly at 100% load?

I personally don't keep my CPU running at 100% 24/7, but for $1,800–$8,800, I should be allowed to without having it reach within 0.3º C / 0.5º F of the processor's point at which transistor functionality starts to break down.

 

[mj_]

I think you're misinterpreting what Tjunction actually is. 100 °C is not the boiling point for transistors at which they magically disintegrate and break for good. Depending on source material some transistors can operate at much higher temperatures while others might stop working at 60 °C or less. Intel specifies that 100 °C is a safe temperature to operate at. Above that the CPU will start to thermal throttle in order to protect its integrated circuits not necessarily from potential damage but in order to ensure reliable operation. In the olden days of yore, long before CPUs started to thermal throttle, they simply froze and stopped working until a reset was performed. Thus, running a CPU at 99.7 °C is absolutely fine and nothing to worry about.

Honestly, what difference does it make to you whether a piece of technology inside a metal case hidden behind a glas screen is running at 99.7 °C, 85.2 °C, or 66.9 °C? At the same time, you insist on quiet operation at full load. You can't have your cake and eat it to. No matter how expensive an iMac is, whether it's $500, $5,000, or $50,000 it cannot overcome the laws of physics or, more specifically in this particular case, thermodynamics.

 

[1229175]

I think you're misinterpreting what Tjunction actually is. 100 °C is not the boiling point for transistors at which they magically disintegrate and break for good. Depending on source material some transistors can operate at much higher temperatures while others might stop working at 60 °C or less. Intel specifies that 100 °C is a safe temperature to operate at. Above that the CPU will start to thermal throttle in order to protect its integrated circuits not necessarily from potential damage but in order to ensure reliable operation. In the olden days of yore, long before CPUs started to thermal throttle, they simply froze and stopped working until a reset was performed. Thus, running a CPU at 99.7 °C is absolutely fine and nothing to worry about.

Honestly, what difference does it make to you whether a piece of technology inside a metal case hidden behind a glas screen is running at 99.7 °C, 85.2 °C, or 66.9 °C? At the same time, you insist on quiet operation at full load. You can't have your cake and eat it to. No matter how expensive an iMac is, whether it's $500, $5,000, or $50,000 it cannot overcome the laws of physics or, more specifically in this particular case, thermodynamics.

I believe you misinterpreted my point. I'm not insisting on silent temperatures; I'm insisting on a lower temperature at high loads. The price of the machine is entirely relevant here. If I purchased a $500 computer, I'd be fine with it having one fan and being within 0.3º C / 0.5º F of Tjunction. iMac is not a $500 computer.

I don't expect Apple to overcome the laws of physics. I expect them to install a second $10 fan in the $1,800–$8,800 machine.

 

[jobinhosyntax]

Honestly, what difference does it make to you whether a piece of technology inside a metal case hidden behind a glas screen is running at 99.7 °C, 85.2 °C, or 66.9 °C? At the same time, you insist on quiet operation at full load. You can't have your cake and eat it to. No matter how expensive an iMac is, whether it's $500, $5,000, or $50,000 it cannot overcome the laws of physics or, more specifically in this particular case, thermodynamics.

High temperatures reduce the efficacy and longevity of components. Apple could have improved the physical constraints of the iMac's thermal design but decided not to, that's what people are highlighting.

 

[jobinhosyntax]

I believe you misinterpreted my point. I'm not insisting on silent temperatures; I'm insisting on a lower temperature at high loads. The price of the machine is entirely relevant here. If I purchased a $500 computer, I'd be fine with it having one fan and being within 0.3º C / 0.5º F of Tjunction. iMac is not a $500 computer.

I don't expect Apple to overcome the laws of physics. I expect them to install a second $10 fan in the $1,800–$8,800 machine.

It seems clear they want these to die in about 3.5 years so users move to Apple silicon.