What would be considered too hot for an idling iMac 27 inch from any of the various sensors?

[Zephar77]

I’ve searched numerous forums and have yet To see consensus on what would be considered the absolute highest windows for temperature readings from the numerous sensors in a iMac 27 inch. “Macs fan control” App as 100°C or 212°F in their notification center as the high for notifications, but this seems awfully hot. This would be momentary episodes under stress, but what about if the machine is just idling or you’re just surfing the Internet?

Some folks say more like 80° - 90°C, or 180° - 190°F. But is this for iMac idling? I suspect temperatures this high at idle could be abnormal, but no one seems to want to commit, not a StatMenus, or any other other no Morris sensor and found monitoring/controlling apps out there. Been using the 14 day trial of capital TG – Pro, and this seems like a very good app app. There’s a $9.99 macOS app called “Temperature Gauge”. Anyone with Experience with this one?

My question to be what would be considered too high when the machine is idling versus under stress. I sometimes get some strange 154°F readings from CPU cores in similar sensors at idle and this seems awfully high. I’ve vacuumed and use compressed air, but have not opened up a late 2014 iMac, but did open up mid 2011 to replace an optical bay fan and end up having to replace the display port cable which is the same one they use a laptop ridiculously fragile and will break easily when you try to put it back in the motherboard.

Any experience or suggestions which app for monitoring the sensors and fans?
Best, Seth

 

[Zephar77]

I noticed temperature gauge is no longer supported for updates because of the necessity to use software that Apple no longer gives permissions. However, you can purchase TG Pro for $10 at the following week they gear ->

TG Pro

Maximize your Mac's performance with TG Pro. The ultimate solution for fan control and extensive temperature monitoring: CPU, GPU, SSD, and more.

www.tunabellysoftware.com

 

[wilberforce]

I used to have a 2014 iMac. I think CPU PECI was around 50C to 60C at idle, and max 100C.

Suggest try Intel Power Gadget to see CPU temps and if it is throttling (max freq decreases).

CPU PKG is basically the same thing as CPU PECI.

Suggest run yes command in Terminal to stress each core in turn:

yes > /dev/null &

Repeat this command for however many virtual (hyperthreaded) cores you have, until all cores are at 100% (Utilization). Check with Activity Monitor, and watch temps and Intel Power Gadget. The fan probably will not increase until CPU PECI reaches about 90C. The CPU should not start throttling until it reaches 100C (its design temperature), at which point fan should be at 2700 rpm.

Terminate by closing Terminal, btw

Doesn't really answer your question, but might help undertand relationship of temps, CPU, and fan speed. At least it helped me.

btw, just because a reading is not the norm, does not mean it is undesirable. A temperature that is above the statistical average is not necessarily "too hot." This might explain why you do not get consistent answers about what is abnormal versus what is too hot.
For example, 90C at idle would be abnormal, but 90C is not too hot for a CPU.

 

[Zephar77]

I used to have a 2014 iMac. I think CPU PECI was around 50C to 60C at idle, and max 100C.

Suggest try Intel Power Gadget to see CPU temps and if it is throttling (max freq decreases).

CPU PKG is basically the same thing as CPU PECI.

Suggest run yes command in Terminal to stress each core in turn:

yes > /dev/null &

Repeat this command for however many virtual (hyperthreaded) cores you have, until all cores are at 100% (Utilization). Check with Activity Monitor, and watch temps and Intel Power Gadget. The fan probably will not increase until CPU PECI reaches about 90C. The CPU should not start throttling until it reaches 100C (its design temperature), at which point fan should be at 2700 rpm.

Terminate by closing Terminal, btw

Doesn't really answer your question, but might help undertand relationship of temps, CPU, and fan speed. At least it helped me.

btw, just because a reading is not the norm, does not mean it is undesirable. A temperature that is above the statistical average is not necessarily "too hot." This might explain why you do not get consistent answers about what is abnormal versus what is too hot.
For example, 90C at idle would be abnormal, but 90C is not too hot for a CPU.

Actually, it does answer my most pressing question, that 50-60ºC at idle is normal. It is in fact a Late-2014 iMac 27", and these are the same temps I am getting, which are higher than my other Mid-2011 27" iMac, which has 3 fans rather than the one for the 2014. I found that strange as it runs much cooler to the touch, the 2014, on the upper back skin of either, yet the temps show it is hotter at idle. I thought maybe I might need to open up to better clean out the dust. I did as best I could with canned air below through the intake ports, and a Dyson from behind out the exhaust. Did not get much dust; but, neither did I from the 2011, after 10 years, which I opened up to change out the Optical Bay Fan which failed. Ended up almost putting to rest as I lost the screen when finished. Turned out the Display Port connector to the mother board must have been brittle as it fell apart on one edge. Surprised to find that one could easily replace this flat cable, and ended up getting one on Amazon. That cable apparently is notorious for messing up one's work on the last connection with that important connector. I will check out your suggestion for the Intl Power Gadget App at -
< https://www.intel.com/content/www/us/en/developer/articles/tool/power-gadget.html > (This is good site?)
Is this the place to procure? I was pleased to see the link I gave recommended something I have used for years, but never read mentioned, Onyx for utility maintenance. For fun, and notice to others that the Display port connection to the mother board is the same on laptops and really has no business being used in a desktop; however, one must be most gentle when inserting that last connection of four cable to that 2011 iMac. Best, Seth
P.S. The first picture is the AFTER replacing the bad cable. Did a nice job on the connector, yes? I suspect it was very brittle, as I treated very gently, yet it still crumbled.

 

[wilberforce]

Some suggestions:
Don't use canned air on intake ports under bottom of monitor. You will just blow dust further in. Some people have got dust inside the corners of the display panel as a result.
There is a screen/grating about 1" above the intake ports at bottom, which you can see with a bright flashlight, which clogs with dust - and is actually good as it prevents at least some dust from going further into the machine.
Turn the machine OFF (important), and instead vacuum with a flat nozzle along the bottom intake ports. Takes about 10 seconds and extracts the dust clogging the grating. I do this every several months.
Yes, Intel Power Gadget v 3.7.0 is the one

 

[CWallace]

My brand new 2020 iMac 5K with a Core-i7 runs between 50° and 60° C whether it is idling or actually doing something with the fans generally around 1200RPM. As I add more load, I notice the fans ramp up, but temps tend to stay in the low-to-mid 60s.

 

[Zephar77]

Some suggestions:
Don't use canned air on intake ports under bottom of monitor. You will just blow dust further in. Some people have got dust inside the corners of the display panel as a result.
There is a screen/grating about 1" above the intake ports at bottom, which you can see with a bright flashlight, which clogs with dust - and is actually good as it prevents at least some dust from going further into the machine.
Turn the machine OFF (important), and instead vacuum with a flat nozzle along the bottom intake ports. Takes about 10 seconds and extracts the dust clogging the grating. I do this every several months.
Yes, Intel Power Gadget v 3.7.0 is the one

My apologies, that is exactly what I did. I slid the pointed edge of my Dyson along the bottom of my 2014 iMac, as well as a 2011 iMac. The grate in the back behind the stand One can clearly see the obstruction of dust and quite easily use the pointed end with the brush seems to work the best there, but then I used both. On the 2011 used canned air along the ports at the top. On the 2011 comma after opening it up, used canned air in the left corner where I believe the CPU/power supply fan is located. I couldn’t figure out where the hard drive fan is located on the 2011 as it has three fans. Once opened I searched everywhere with a flashlight and could not find it. I searched everywhere in the Internet and never could get an answer, but I suspect you have to remove the logic board to see it. I saw a different earlier Mac taken apart and there was a small round fan behind the logic board. I could purchase a hard disc fan but nobody gives directions on how to replace it anywhere on a mid – 2011 iMac 27 inch. Anyone have experience with this or knowledge? Best, Seth

 

[Zephar77]

My brand new 2020 iMac 5K with a Core-i7 runs between 50° and 60° C whether it is idling or actually doing something with the fans generally around 1200RPM. As I add more load, I notice the fans ramp up, but temps tend to stay in the low-to-mid 60s.

Thank you, that’s what I’m getting on my late 2014 i5. It never seems to change that 1200 RPM, which is somewhat suspicious. And it’s getting in the 170°F+ range, Which is closer to 80°C, which I thought was too hot, but the fan still remains at 1200 RPM. However, I can increase the RPM with Macs fan control, so I guess it works; but does the sensor work to regulate the RPMs?

 

[Hombre53]

I use Macs Fan Control on my late 2013 Core i5, 27" iMac. The internal cooling fan is set at 1800 rpm, that keeps the temps around 90F-95F. I had to replace the cooling fan a few months ago because it was starting to make a lot of noise. I blew the inside of the iMac out with canned air to keep the accumulated dust to a minimum. All good.

 

[Zephar77]

I use Macs Fan Control on my late 2013 Core i5, 27" iMac. The internal cooling fan is set at 1800 rpm, that keeps the temps around 90F-95F. I had to replace the cooling fan a few months ago because it was starting to make a lot of noise. I blew the inside of the iMac out with canned air to keep the accumulated dust to a minimum. All good.

I might try that as keep getting temperatures of over 170°F idling. Looking at the history of the fan it never changes from 1196 to 1200 RPM. I would think the fan would increase in RPMs between 60°C and 70°C, yes? in fact, think I’ll try that right now and put the fan at 1800 RPM as you did and see how it goes. Best, Seth

 

[Zephar77]

I use Macs Fan Control on my late 2013 Core i5, 27" iMac. The internal cooling fan is set at 1800 rpm, that keeps the temps around 90F-95F. I had to replace the cooling fan a few months ago because it was starting to make a lot of noise. I blew the inside of the iMac out with canned air to keep the accumulated dust to a minimum. All good.

I set it at 1777 and temperatures iStat Menus show a sharp decrease in temperature of all the CPU cores and other temperature sensors, but increase in wattage and slight increase in temperature of the fan area. Yeah, I’m not understanding why the computer doesn’t kick in the fan when it gets over 170°F? It just stays like it’s stuck at
1200 RPM?

 

[acorntoy]

2009 27 iMac with original i7 is always boiling ? Day I don’t hear the fans I’ll assume one failed.

 

[wilberforce]

I set it at 1777 and temperatures iStat Menus show a sharp decrease in temperature of all the CPU cores and other temperature sensors, but increase in wattage and slight increase in temperature of the fan area. Yeah, I’m not understanding why the computer doesn’t kick in the fan when it gets over 170°F? It just stays like it’s stuck at
1200 RPM?

My 2020 iMac fan does not increase from 1200 rpm until the CPU temp gets to about 90C.
It is not a problem for a CPU to run continuously at 90C, it will not throttle at that temp, so there is no need for additional airflow.
One might intuitively think the airflow should be increased at that temp, but if there is no issue running at 90C, why increase the fan and just make extra noise? Then people would complain about unnecessary fan noise. I think it is a deliberate design choice, to minimize fan noise when it is not necessary.

 

[Zephar77]

My 2020 iMac fan does not increase from 1200 rpm until the CPU temp gets to about 90C.
It is not a problem for a CPU to run continuously at 90C, it will not throttle at that temp, so there is no need for additional airflow.
One might intuitively think the airflow should be increased at that temp, but if there is no issue running at 90C, why increase the fan and just make extra noise? Then people would complain about unnecessary fan noise. I think it is a deliberate design choice, to minimize fan noise when it is not necessary.

Thank you for the answer. I have not seen that in quite a bit of searching. What are you saying make sense.
So, I should let the fan run by the sensors and that the fan stayed at 1200 RPM?

 

[Fatus_Asticus]

It’sa small unit and heat management is important for longevity. I personally use macfancontrol to customize my fan curve because Apple has this weird obsession of not wanting to use fans until heat buildup is at a high level.

People have this obsession with fans not coming on and I don’t get it. I run my fans at low rpm all the time on my mbp and it makes a huge difference keeping things cool.

I’m using the M1 which is efficient. The i5 or i7 are some serious heat generators and I would be even more aggressive with those chips.

 

[wilberforce]

Thank you for the answer. I have not seen that in quite a bit of searching. What are you saying make sense.
So, I should let the fan run by the sensors and that the fan stayed at 1200 RPM?

Well, I'm just letting you know that my relatively new 2020 iMac does not typically increase the fan speed until CPU reaches about 90C. So if yours does something similar, then there is nothing "wrong" with it, as that is what Apple have designed it to do, and there doesn't appear to be any harm in doing so, IMO.
If you personally want to have cooler temps and higher fan speeds, then utilities like Macs Fan Control, especially the paid versions, can provide this.
Some people have done the opposite, reducing fan speeds below 1200 rpm, to reduce fan noise that bothers them

 

[Zephar77]

Well, I'm just letting you know that my relatively new 2020 iMac does not typically increase the fan speed until CPU reaches about 90C. So if yours does something similar, then there is nothing "wrong" with it, as that is what Apple have designed it to do, and there doesn't appear to be any harm in doing so, IMO.
If you personally want to have cooler temps and higher fan speeds, then utilities like Macs Fan Control, especially the paid versions, can provide this.
Some people have done the opposite, reducing fan speeds below 1200 rpm, to reduce fan noise that bothers them

Only thing that concerns me is that I’ve been running iStat Menus four years on the 2014, and has been in the mid 30s to low 40s, and there was more variation in the fan speed. It’s the change that I was wondering what has changed?
Perhaps it was an update to iStat Menus? I know I read somewhere that from the developers of temperature gauge/TG-Pro, I believe, stated Apple would not allow updates to their App in their App Store any longer because they were not giving permission to access to some software kit to retrieve temperatures from the sensors?
I’m wondering if this has something to do with it?

 

[Hombre53]

I recently retired my vintage late 2009 iMac (27" Core i5). It ran Macs Fan Control for its entire life. That iMac has 3 fans, one for the CPU, CDRom and HDD. Without Macs Fan Control, the computer would run hot, usually 145-150F plus. With fan control: 2200 rpm CPU fan, 2400 rpm CDRom and HDD Fans, the temp drops to 90F. Big difference, but noticeable fan noise. I'd rather keep the computer cool so I'm good with the extra fan noise/rpm's.Once a year I'd clean out the insides (canned air) to keep it clean. After 12 years of service, no electronics failures due to heat, etc.

 

[Zephar77]

I recently retired my vintage late 2009 iMac (27" Core i5). It ran Macs Fan Control for its entire life. That iMac has 3 fans, one for the CPU, CDRom and HDD. Without Macs Fan Control, the computer would run hot, usually 145-150F plus. With fan control: 2200 rpm CPU fan, 2400 rpm CDRom and HDD Fans, the temp drops to 90F. Big difference, but noticeable fan noise. I'd rather keep the computer cool so I'm good with the extra fan noise/rpm's.Once a year I'd clean out the insides (canned air) to keep it clean. After 12 years of service, no electronics failures due to heat, etc.

I have the med – 2011 version of yours and the fans are controlled by the sensors and they are

I recently retired my vintage late 2009 iMac (27" Core i5). It ran Macs Fan Control for its entire life. That iMac has 3 fans, one for the CPU, CDRom and HDD. Without Macs Fan Control, the computer would run hot, usually 145-150F plus. With fan control: 2200 rpm CPU fan, 2400 rpm CDRom and HDD Fans, the temp drops to 90F. Big difference, but noticeable fan noise. I'd rather keep the computer cool so I'm good with the extra fan noise/rpm's.Once a year I'd clean out the insides (canned air) to keep it clean. After 12 years of service, no electronics failures due to heat, etc.

My mid-2011 iMac has very sensitive sensors controlling the fans(3) and they change minute by minute to keep the temperatures cool and currently running at 2400/1600/1700 RPM, whereas my Late 2014 is always 1200 RPM and never changes outside of window of 1196–1206 RPM with temperatures above 76°C. The 2014 is doing nothing but showing photos from my photo library in screen saver mode. It only has the one fan, but I’m surprised the newer iMac is not more sensitive in changing the velocity of that fan. I believe you or someone else mentioned that there newer iMac fan did not increase in velocity until it was 80°C or 90°C - awfully hot. Is Apple trying to shorten the life of iMac’s, because my 2011 is working great, but so is a 2014. However the temperatures were much cooler until recently, but I was not paying attention to the RPM of the fan to see if it was accommodating higher temperatures with changes in RPM. That’s why I asked the question here thinking perhaps something happened with the controlling of the fan rpm. I took it off auto and placed it on manual at 1726 RPM and that does a much better job keeping it cooler.
Again thank you for your input. I think I will keep it in manual hey Siri you have done, but it was staying cool until today over the past week after giving a good dusting, but only from the outside areas access points. Best, Seth