iMac 2017 i5 loud fan and high cpu in idle

[Christian92]

Hello,

yesterday I received a base iMac 27 with i5 3.4. After 30 minutes of installing some apps, the fan got really loud and the cpu usage was high. I thought it might be related to the installations.

But today the same. I opened Safari to download Mac Fan Controll and it got really loud again with a constant CPU usage above 60%.

According to Macs Fan Control the main fan has currently 3600 RPM (from max 2700?!). The temperatures are also really normal.

Even the graphics don't feel fluid when this happens.

Can someone help me what might be the problem?

 

[mreg376]

That kernel task looks like the culprit, obviously. I assume you have rebooted, and know all the programs that are autoloading on startup? And you're on the current version of High Sierra?

 

[Christian92]

Yes I rebooted and turned it off but the fan and the high cpu was still the same.
Autoloading shouldn’t be a problem, I only installed some apps I use on my MacBook like Affinity and WhatsApp from the Mac App Store but I didn’t use any of them.

 

[mreg376]

Rebooting restarts the kernel, so if rebooting doesn't solve the problem you have an issue. It could be a kernel extension, like something connected to third party software or a hardware driver. You may try restarting in safe mode, which does not load any kernel extensions, and see if the problem persists.

 

[wardie]

Run terminal and check out any non-Apple kernel extensions with this command "kextstat | grep -v com.apple" You should probably have little or no stuff come up on a vanilla Mac but it may give you a clue on any installs that are causing a problem...

 

[Fishrrman]

Try this "as a test only".

Turn off wifi, if it's on.
Turn off the iMac.
DISCONNECT ethernet, if it's connected.
Reboot (without any internet connection.

Do the fans still run wild?

 

[Icy1007]

Try booting your Mac into safe mode and see if the issue happens there. If it doesn't then it is something that is getting loaded into the kernel.

https://support.apple.com/en-us/HT201262

 

[Christian92]

I just reseted SMC, NVRAM but nothing changed. Then I ran the diagnostics and got the message, that the SMC is caused by SMC (Code PFM006). So it seems that I have to return it...

 

[cwanja]

I just reseted SMC, NVRAM but nothing changed. Then I ran the diagnostics and got the message, that the SMC is caused by SMC (Code PFM006). So it seems that I have to return it...

My assumption would be a failed sensor.

 

[ondert]

LOL.. looks like the exact same problem. My 2016 15” MacBook Pro had the same problem. I brought my mac to apple store and then we found out it’s related to a software. Just delete “macs fan control”, then your mac will turn to normal. It leds to this problem. Somehow it makes your mac think the cpu is under pressure and use kernel task to throttle and cool it. However, in reality everything works fine. I don’t use that program anymore.

 

[MBAir2010]

Is your surrounds humid?
My MacBook Air is having more fan usage lately.
Some really reliable member here advised someone not using an app that measures fan speed during the summer, because that wears down the cpu, graphics and overall performance of the Mac.

 

[Christian92]

I installed Macs Fan Control on the second day, after the first CPU and fan problems to check if the fan is on 100% or the temperature is too high.
On the other hand I use Macs Fan Control daily on my MacBook Pro 2017 because it gets unusable hot in my office in summer before the fans turn on. And I never had any issues with it on my MacBook for years.
But I could deinstall Macs Fan Control and try to reset SMC and NVRAM.

 

[ondert]

Hmm.. I missed this. What did you installed on the first day? Your problem looks like a software issue.

 

[chscag]

I just reseted SMC, NVRAM but nothing changed. Then I ran the diagnostics and got the message, that the SMC is caused by SMC (Code PFM006). So it seems that I have to return it...

Yes, return it. I have the same exact machine and Macs Fan Control shows the fan running at 1200 RPM with a temp of around 43 degrees C. Even under heavy load the fan rarely exceeds that with maybe a temp of around 50 C. It appears your System Management Controller is out of whack.

 

[Christian92]

Hmm.. I missed this. What did you installed on the first day? Your problem looks like a software issue.

Nothing special, some apps I bought in the App Store (Affinity, WhatsApp, iWork Apps, FPT, Password Manager) and the newest macOS update. Actually I only opened WhatsApp, Safari and Notes at this time.
The fan was already loud 10-15 minutes before the macOS update and stayed loud during the update. Afterwards as well with the kernel_task on very high percentage (this could be before, but I didn't checked it).

 

[Fishrrman]

Create a new user account that has NOTHING in it (software-wise).
This is "for test purposes only" -- you can delete it afterwards.
Shut down and boot into this test account.
Check activity monitor.
Does anything change?

 

[Christian92]

I just made a complete reset and reinstall and ran the diagnostic with the same SMC error. Then I unplugged the power cable to reset the SMC. No errors in diagnostic. So I thought, problem solved and followed the setup.
5 minutes after the fresh installation, the same thing happened again (screenshot).

So now I have to reset it again and sent it back
I hope they will accept the error, because in the first diagnostic with reseted SMC it will be fine again for a moment...

 

[chscag]

Like I said above, take it back, the SMC is not right. You're just going to be battling windmills with that machine. Get a replacement.