Fans running at max speed though temperatures and cpu clock are low

[TheRiddler1982]

Hi all,

I have a Mid 2018 Macbook Pro with Vega 20 graphics unit running MacOS 10.14.6. What I notice since 2 months is the fact that the fan control somehow doesn't work. The fans are spinning at max rpms and both temperatures and cpu clock speed (utilization) are low. I have made a screenshot from iStats Menu to show you the exact figures. It takes about 20 minutes to slow down.

I already tried TurboBoost Switcher but with no effect. Do you have this behavior too? I made an NVRAM reset with no effect. Fans kick in to earlier and take too long to slow down.

Do I need to reinstall my OS?

Thanks for any help!

 

[Thysanoptera]

Show the whole sensors page from iStatsMenu. Also that software has its own fan control functionality, check if you didn’t accidentally set some weird fan curve.

 

[casperes1996]

In addition to what Thysanoptera said;

NVRAM reset should generally not affect this particular issue, but an SMC reset could. The SMC is mainly in control of the fan speeds. Though it's more likely to be iStat overriding it.

 

[TheRiddler1982]

I didn't find any fan curve. Just the thing you see in the screenshot. How can I configure iStat not to play with the SMC settings? What additional sensor data do you need?

 

[Thysanoptera]

I didn't find any fan curve. Just the thing you see in the screenshot. How can I configure iStat not to play with the SMC settings? What additional sensor data do you need?

This is definition of fan rules, not what mode are in right now. When you open Sensors, the first line at the top is “Fans”. It should read “System controlled”. If it says “Automatic fan rules” iStatMenu will use what you showed in the last screenshots, which is just fixed value.

 

[TheRiddler1982]

It says "system-controlled". The fans slow down at some point but it takes 15min to go back at 2100rpms. That's what I am curious about. Why are the fans spinning at max if the temperature is low and CPU utilization is near 0%?

 

[Thysanoptera]

It says "system-controlled". The fans slow down at some point but it takes 15min to go back at 2100rpms. That's what I am curious about. Why are the fans spinning at max if the temperature is low and CPU utilization is near 0%?

Ok, then it is not iStatMenu. Reset SMC like @casperes1996 said. https://support.apple.com/en-us/HT201295#t2

If that won't help post a screenshot of the whole sensor page from iStatMenu.

 

[TheRiddler1982]

I think the SMC reset made it better . Had never such problems before with the Macbook Pro 2012 Retina. Good old thing

 

[chrizzz09]

Have you checked if the GPU is being used at the moment? The GPU has a different fan sensor, so maybe your GPU is being taxed and thus the fans spin up to cool your GPU while your CPU is not being used.

 

[TheRiddler1982]

No, I haven't thought about that. I will monitor it the next time I will see that behavior. Thanks for hint.

 

[TheRiddler1982]

Talking about the devil: the issue is now up again. Here are the details about iStat. None of the components drew much power. Any idea what is causing it?

 

[casperes1996]

Talking about the devil: the issue is now up again. Here are the details about iStat. None of the components drew much power. Any idea what is causing it?

I'm not so familiar with iStat menus. It might have the same feature, but I'm going to advice through Activity Monitor.

Open Activity Monitor, and look for "Requires High Power GPU" or something like that. I forget the phrasing. Sort by it, and see if any apps activate the Radeon.
The only thing I found odd in your iStat numbers was that the Intel GPU was set to frequency 0MHz, which to me suggests an active Radeon.

 

[Honza1]

Talking about the devil: the issue is now up again. Here are the details about iStat. None of the components drew much power. Any idea what is causing it?

If you are charging very depleted battery, it takes lot of power, heats up the system as battery is huge heater while being charged (or discharged). So if the battery is NOT charged, this is normal behavior and should normalize when battery is charged....

If you have charged battery, then this is confusing. On my system the DC in and System total basically agree (on power source while not charging battery).
And system total is rough sum of CPU needs and graphics card (this is roughly as it does not include display, I guess).
There are huge discrepancies in your screen grab. Where is all that power going?