Just an observation about the heat the Mac mini generates while sleeping

[whitby]

I have an M4 Pro Mac Mini with 64GB memory and a 2TB SSD. It is connected to an external TB5 4TB drive and to a TB5 hub to which is connected a TM drive and a slower TB3 4 Disk RAID 5 disk array. The Mini is also connected to 2 5K monitors, one Apple Studio (directly) and one LG Ultrafine 5K monitor (via the hub). I have a wired mechanical keyboard and Logitech MS Master 3S, I think it is, mouse plus an Audioengine active loudspeaker system with a sub plus a studio microphone.

So why the post? It is the fact that this system runs hot whether or not it is in sleep mode. The fans do not run in sleep mode and rarely run in operational mode but the case does reach around 40 - 50 deg C. ie quite warm to the touch. iStat shows CPU temps around 53 deg C so not excessive. I do not have it set to allow incoming messages and incoming network activity etc. to wake it up and I allow drives to sleep when possible (which never occurs) but I do have TM running and there are a series of back up tasks via Carbon Copy Clone that run once a week. Each day I come down to use the machine it is quite warm to the touch and sometimes hot (both it and the external TB5 drive) which means they have been active, but iStat history shows no real activity. As a result of this I have started shutting down the machine at night to give it some thermal rest and guess what? That inaccessible power button becomes an issue. The one we all complained about but never really let it concern us, since when do we really shut down our Macs? I had a 2020 i9 iMac that was running from the day I started it up to the day I shut down and sold it. No issues.

Has anyone else experienced this? Maybe I am being overly concerned and Apple expect this to run hot continuously for 5 years or more. I think not, but I find it ironic that 1) I feel the need to shut it down due to the heat it generates and 2) this is the one machine where the power button is inaccessible.

Note I have gone through all the apps looking for background refreshes etc. other activities and stopped where not required. I am also aware that Apple keep the TB and USB ports powered on while sleeping so if the peripheral cannot detect a sleep state it will stay active, which is probably the case with the 4TB TB5 drive.

So, again, has 1) anyone else noticed this and 2) have you found a magic way to stop this behavior while it is sleeping.

 

[MacCheetah3]

So, again, has 1) anyone else noticed this

Yes.

2) have you found a magic way to stop this behavior while it is sleeping.

No — more specifically, nothing consistent.

Perhaps coincidence, but macOS 15.5 or 15.6 does appear to improve the situation for my setup. That is, the Mac doesn’t appear to wake up quite as often (i.e., external drive lights) and the Mac as well as external drives don’t seem quite as hot — and it’s summer, so the indoor temps hover much closer to 80ºF.

Each day I came down to use the machine and it is quite warm to the touch and sometimes hot (both it and the external TB5 drive) which means they have been active, but iStat history shows no real activity.

At first, this concerned me (a little), especially regarding the external SSDs. And there does seem to be a connection between Mac minis exhibiting these characteristics and having external drives. Nonetheless, they’re all definitely within spec, and I haven’t noticed any ill affects whatsoever. Therefore, meh, not worried any longer.

As a result of this I have started shutting down the machine at night to give it some thermal rest and guess what? That inaccessible power button becomes an issue. The one we all complained about but never really let it concern us

I’m still using a vertical Mac mini mount I purchased for my 2012 Mac mini, though with the 2024 Mac mini placed atop regularly (horizontal). Thus the power button is especially not a problem. You could put something as simple as a drink coaster or two underneath the mini to make the power button access less obstructed.

By the way, raising the mini off the surface doesn’t appear to affect err improve thermals, unlike the Intel versions.

 

[casperes1996]

The cpu temperature was low, the fans weren’t spinning up. While the casing itself, as part of the heat sink system may be heatsoaking, it’s not a handheld device. They don’t need skin temperature aware power management.

Even if your old iMac was colder to the touch (with fan spin especially) it was probably warmer inside especially under use. My old iMac would reach 108C with fan spin og 3200RPM under heavy use. Way higher than the nominal max fan speed of 2700.

Frankly I just wouldn’t worry about it with internal temperature so low. The casing temperature isn’t what matters but the component temperature and if it has headroom to increase fan spin then it’s fine.

You can set a higher fan speed yourself if that makes you feel more comfortable.

I of course can’t speak to your external equipment and the power consumption cost of it all being in a powered non-sleep state but I wouldn’t worry about the Mac’s thermal situation based on what you’ve said.

 

[whitby]

The cpu temperature was low, the fans weren’t spinning up. While the casing itself, as part of the heat sink system may be heatsoaking, it’s not a handheld device. They don’t need skin temperature aware power management.

Even if your old iMac was colder to the touch (with fan spin especially) it was probably warmer inside especially under use. My old iMac would reach 108C with fan spin og 3200RPM under heavy use. Way higher than the nominal max fan speed of 2700.

Frankly I just wouldn’t worry about it with internal temperature so low. The casing temperature isn’t what matters but the component temperature and if it has headroom to increase fan spin then it’s fine.

You can set a higher fan speed yourself if that makes you feel more comfortable.

I of course can’t speak to your external equipment and the power consumption cost of it all being in a powered non-sleep state but I wouldn’t worry about the Mac’s thermal situation based on what you’ve said.

My ambient temperature is 24C so the case is often 26C higher which feels hot. My 27” iMac could get hot (the air exhaust temp of the vents could reach 60 C or do) but I never recorded high cpu temperatures while in sleep mode. Hence my cause for concern.

Anyway I think the gist of the two responses I have received so far is live with it, they do that. I am going to keep monitoring the situation and will investigate making the power button more accessible without blocking the antenna for the WiFi, although I do have a wired Ethernet connection as well.

 

[MacCheetah3]

Another couple of points I forgot to make:

The 2024 Mac mini design has the power supply on top rather than along the side. So, most of the heat you feel on the top case is from that.

For the second point, I’ll swing back to:

And there does seem to be a connection between Mac minis exhibiting these characteristics and having external drives.

If you have multiple (bus) powered drives connected, obviously, that puts more load on the PSU.

Ultimately, it’s probably more about how often the Mac wakes up to do intermittent tasks.

You could try some experimenting with Power Nap:

Turn Power Nap on or off on Mac

Choose whether Power Nap is on or off when your Mac is connected to a power adapter or using battery power.

support.apple.com

 

[whitby]

Another couple of points I forgot to make:

The 2024 Mac mini design has the power supply on top rather than along the side. So, most of the heat you feel on the top case is from that.

For the second point, I’ll swing back to:

If you have multiple (bus) powered drives connected, obviously, that puts more load on the PSU.

Ultimately, it’s probably more about how often the Mac wakes up to do intermittent tasks.

You could try some experimenting with Power Nap:

Turn Power Nap on or off on Mac

Choose whether Power Nap is on or off when your Mac is connected to a power adapter or using battery power.

support.apple.com

Thanks for the info. I had not thought about the PSU location.

Power Nap is only available on Intel based machines.

 

[ScanPro]

I have the same cpu set up, only the base 24Gb. I also, have a 4TB and a 2TB both 990's in OWC 1M2 enclosures attached to the mini, with a powered TB5 dock to the 3rd port. The mini usually runs around 40-45 degrees C. depending on the apartment temp. Mac fan is set to 1250 all the time. If I decide to run a game I will run it up to 2500, the Mini is barely warm to the touch. I don't think it is much to be concerned about. Too many threads on the Mini temp issue.

 

[whitby]

Too many threads on the Mini temp issue.

Lots about running temperatures but very few that I could find about temperature while it was sleeping, hence my post.

 

[MacCheetah3]

Lots about running temperatures but very few that I could find about temperature while it was sleeping, hence my post.

Are apps able/allowed to log (for more than a maybe a few minutes) during sleep states?

Related:

Mac Sleep Modes: Sleep, Hibernate, Safe Sleep, and Standby

Explore the differences between Mac sleep modes: Sleep, Hibernate, Safe Sleep, and Standby and choose the best for your needs.

macbookjournal.com

What does my Mac do while sleeping all night long?

can someone please explain to me what my Mac does while asleep? I am running the latest version of Big Sur (11.4 (20F71)), so I think this is intentional, but I'm not sure why. I have turned off al...

apple.stackexchange.com

 

[ScanPro]

43 C this morning after a good night's sleep.

 

[whitby]

Are apps able/allowed to log (for more than a maybe a few minutes) during sleep states?

Related:

Mac Sleep Modes: Sleep, Hibernate, Safe Sleep, and Standby

Explore the differences between Mac sleep modes: Sleep, Hibernate, Safe Sleep, and Standby and choose the best for your needs.

macbookjournal.com

What does my Mac do while sleeping all night long?

can someone please explain to me what my Mac does while asleep? I am running the latest version of Big Sur (11.4 (20F71)), so I think this is intentional, but I'm not sure why. I have turned off al...

apple.stackexchange.com

No, the only app that may log in, but then only once per week, is CCC (Carbon Copy Cloner) but then it is continuously running to check system time for events, but uses very little resources when it does run. I disabled it for a while and it made no difference. One odd thing is that this morning the case temp was down to 37C which is the lowest I have ever measured. We keep our house at a fairly constant 24C (we have two AC units, one for each floor) so it was not a change in ambient temperature that caused this reduction. This was after a shutdown for 24 hrs and restart, so maybe a service was stopped and did not restart. I will look at the daemons that are running and compare before and after.

 

[!!!]

iStat history shows no real activity

When sleeping, does iStat show full graph history, or are parts of it blanked out? If it's showing the full graph, your mac isn't really sleeping. If there are blanks in the graph, your mac is sleeping (and the times when it does briefly wake will be shown where iStat's graph has bits of data.

I have found this to be the case, even with my M1 MBA, it will wake a few times during the day when its lid is shut. But if it fails to sleep for whatever reason, the iStat graph will show continuous data in the graph for the times it should've been sleeping.

I don't normally sleep my M4 mini, but when I did I had the feeling that it did not really go to sleep. I have some external drives connected 24/7, which may be why.

 

[whitby]

When sleeping, does iStat show full graph history, or are parts of it blanked out? If it's showing the full graph, your mac isn't really sleeping. If there are blanks in the graph, your mac is sleeping (and the times when it does briefly wake will be shown where iStat's graph has bits of data.

I have found this to be the case, even with my M1 MBA, it will wake a few times during the day when its lid is shut. But if it fails to sleep for whatever reason, the iStat graph will show continuous data in the graph for the times it should've been sleeping.

I don't normally sleep my M4 mini, but when I did I had the feeling that it did not really go to sleep. I have some external drives connected 24/7, which may be why.

IStat is showing all data during the sleep, so I tried uninstalling and seeing if it made any difference. It made no difference at all. The trouble with Mac OS sleep set up is that it has no options, it is either sleeping or it is not. I stopped Time Machine, CCC, iStat and it did not change the running temperature. However I have noticed that after the last reboot (I have done several) and allowing Time Machine (which is always configured to backup once a week), iStat and CC to run as per normal, the case temperature has suddenly dropped to 34C in sleep, which is 10 to 15 C cooler than it has been running. IStat shows the temperature drop (along with a CPU temp drop) at the time of reboot. So something was running in the background. I checked the daemons that are running and they do not appear to have changed. Odd, to say the least.

 

[mrblog47]

Me too. Base M4 Mac Mini, 24GB 512GB. Also have a Samsung T2 SSD always connected but I'm not sure if that makes any difference. During typical use, I see between 10% to 20% CPU usage and almost always around 17GB RAM. Was also wondering why it's always warm. Strange, given the same chip is in my iPad Pro 1TB/16GB. Maybe the built in power supply causes more heat. I would assume this is offset by having active cooling.

 

[ChrisA]

Your mini is powering a lot of external devices. Even if it is doing nothing, it is still powering all that stuff. It uses the case as a heat sink.

It is just a matter of thermodynamics that to move heat, the heat sink needs to be much higher than the air

 

[MacCheetah3]

An also important note:

https://forums.macrumors.com/threads/samsung-990pro-4tb-pcie4-0x4-nvm-express-2-0-in-acasis-80gbps-m-2-nvme-ssd-enclosure-for-mac-mini-m4-pro.2447387/post-33678129

Your mini is powering a lot of external devices. Even if it is doing nothing, it is still powering all that stuff. It uses the case as a heat sink.

It is just a matter of thermodynamics that to move heat, the heat sink needs to be much higher than the air

 

[mrblog47]

Your mini is powering a lot of external devices. Even if it is doing nothing, it is still powering all that stuff. It uses the case as a heat sink.

It is just a matter of thermodynamics that to move heat, the heat sink needs to be much higher than the air

ah yes, good point. Every Thunderbolt and USB-C port on mine is currently connected to something. I guess that makes a difference.

 

[whitby]

An update:

My Mini, after a period of having case temperatures of around 45 to 50C while sleeping is down to 34 to 35C after the last reboot (I had tried this a few times before without any reduction in case temperature whilst sleeping). My ambient is 24C. The only non self powered device connected to my Mini is a Trebleet Thunderbolt 5 drive which does not sleep when the Mini sleeps ( you can hear the fan running and the activity light is on). This is despite me setting the option for the system to sleep the drives when not using them, which is mildly irritating.

I am concerned that the external drive fan will prematurely die since it never turns off but apart from ejecting it and unplugging it, there seems to be no way to stop or power down the external drives. The case on the external drive is around 34C when the Mini is sleeping.

So I am still mildly concerned that my Mini runs 10C above ambient when sleeping and the external TB 5 drive never sleeps and the little fan never stops while connected to the Mini. Long term reliability is a serious concern here. BTW I purchased a rather nice wooden stand for my Mini that gives easier access to my power button.

 

[theluggage]

The only non self powered device connected to my Mini is a Trebleet Thunderbolt 5 drive which does not sleep when the Mini sleeps ( you can hear the fan running and the activity light is on). This is despite me setting the option for the system to sleep the drives when not using them, which is mildly irritating.

Well, that would pretty much account for the problem. If the device is non-self-powered and not sleeping then its drawing power from the Mac Mini so that will heat up. Also, I believe SSDs do garbage collection when they're idle.

However, decent-quality electronics should be capable of running 24/7/365 even if the fan is running. Arguably, a device is more likely to fail if its continually being started or stopped because of current spikes, thermal expansion/contraction etc. Nothing lasts forever - esp. if its designed for planned obsolescence by (e.g.) making it difficult or impossible to clean/replace parts like fans.

More relevant, perhaps, is that with current energy prices, having that Mini & SSD running 24/7 is costing you real cash-y money. Maybe not a fortune, but money you don't necessarily need to spend.

(Which, folks, is why the Mac Mini should have an accessible freaking power switch!)

 

[whitby]

Well, that would pretty much account for the problem. If the device is non-self-powered and not sleeping then its drawing power from the Mac Mini so that will heat up. Also, I believe SSDs do garbage collection when they're idle.

However, decent-quality electronics should be capable of running 24/7/365 even if the fan is running. Arguably, a device is more likely to fail if its continually being started or stopped because of current spikes, thermal expansion/contraction etc. Nothing lasts forever - esp. if its designed for planned obsolescence by (e.g.) making it difficult or impossible to clean/replace parts like fans.

More relevant, perhaps, is that with current energy prices, having that Mini & SSD running 24/7 is costing you real cash-y money. Maybe not a fortune, but money you don't necessarily need to spend.

(Which, folks, is why the Mac Mini should have an accessible freaking power switch!)

That would be fair except the TB5 enclosure only consumes 3 watts when idling (I have monitored voltage and current consumption). I am not sure I would expect a 10C rise in temperature above ambient for such a low power requirement. When under full load power consumption goes up to 25 Watts, peak with around 15 Watts average. Hardly earth shattering. Mini TB5 ports are rated for 140 Watts. This unit has a Samsung 990 Pro 4TB SSD.

 

[maflynn]

That would be fair except the TB5 enclosure only consumes 3 watts when idling

Unplug all external devices and monitor the temps, see if you're mini's temps decrease when going to sleep with no peripherals attached.

 

[whitby]

Unplug all external devices and monitor the temps, see if you're mini's temps decrease when going to sleep with no peripherals attached.

I have and it makes no difference to the case temperature. I sleep the mini and then remove all peripherals, including monitors and keyboard (keyboards I use are mechanical and are wired, connected via the monitor). The problem, of course, is you cannot tell if the mini wakes up when you remove the peripherals. I eject the drives prior to sleeping of course.

 

[maflynn]

I have and it makes no difference to the case temperature.

Sounds like maybe you have a mini with a poor thermal paste job done on it.

Don't know your skill level, nor the complexity of taking apart the mini, but repasting may be an option

 

[MacCheetah3]

I think, it’s still about how your mini isn’t sleeping or napping much. If you want to continue the pursuit, another troubleshooting step reminder is creating a new/fresh local user account. Don’t log into your Apple Account and skip setting up any services prompted, unless you need them (e.g., accessibility). You can either go about dedicating specific time for testing or whenever you would normally have your mini idle, log out of your normal/main account, move to this fresh test account and sleep the Mac, observe if it sleeps and stays cool for long (e.g., hours). Although, for the most accurate results, a robot and log into the fresh account would be best.

Ultimately, I recommend not putting a huge concern upon it.

P.S. Even though I’m no longer worrying and the following is not a necessity, I’m going to try getting into the habit of shutting down my Mac more routinely if it seems I won’t be using it for a few hours or more. In part, I feel I’m getting a little lazy in that regard. It’s probably about 15 seconds from pressing the power button to up and running with whatever app (e.g., web browser) you need. Again, the physical wear (fan, thermals, SSD, etc.) on the system is likely negligible to cause any problem, but why add subject it to any additional wear just to save 30 seconds or so? Of course, this routine is relevant to your frequency of use.

 

[casperes1996]

Sounds like maybe you have a mini with a poor thermal paste job done on it.

Don't know your skill level, nor the complexity of taking apart the mini, but repasting may be an option

If the outer casing gets hot that indicates good thermal conductivity from the inner components. Bad thermal paste application would result in a hot chip that cannot properly emit its heat throughout the heat sink so lower temperatures on the heat sink and casing but very high soc temperatures