Bad fan curve customization in NUC8i7BEH

[Konstantin]

I have Intel NUC8i7BEH with Ubuntu Linux 19.10

Kernel version: 5.3.0-24-generic

 BIOS version: BECFL357.86A.0077.2019.1127.1452

By default "Balanced" cooling profile was selected in BIOS. In this profile fan speed is 2300rpm with system IDLE and basic OS usage, which is loud and uncomfortable for me.

After read other questions in the forum

* https://forums.intel.com/s/question/0D50P00004EgUqNSAV/nuc8i7beh-high-fan-noise

* https://forums.intel.com/s/question/0D50P0000490SGwSAM/nuc6i7kyk-skull-canyon-nuc-runs-hot

* https://forums.intel.com/s/question/0D50P0000490GfRSAU/nuc6i5syh-cpu-80c-and-fan-4000rpm-playing-league-of-legends

I use the "Custom" profile with following settings:

         Fan Control Mode: Custom

Primary Temperature Sensor: Processor

       Fan off capability: off

      Minimum Temperature: 75

   Minimum Duty Cycle: 20

     Duty Cycle Increment: 4

 Second Temperature Sensor: Memory

      Minimum Temperature: 65

   Minimum Duty Cycle: 20

     Duty Cycle Increment: 4

Now fan speed is 1300rpm and process temperature is around 40-42C during basic operation system usage, e.g. browsing in the internet. So, fan sound is comfortable.

But, if perform some heavy tasks fan SUDDENLY becomes VERY loud (> 4000rpm). The problem here is fan doesn't increase speed when temperature comes closer to the Minimum Temperature. I expect more smooth fan curve, e.g. like this https://github.com/pop-os/system76-power/blob/7a43106205b63d159b2c17ef848f3f9abbcaed19/src/fan.rs#L218-L227:

 Temperature | Duty

-------------+------

 < 40       | 0   

 40         | 10  

 45         | 30  

 55         | 35  

 65         | 40  

 75         | 45  

 80         | 50  

 90         | 100

Moreover, fan speed sensor is not detected by Linux Kernel, and therefore it's not possible to control fan speed from OS level.

So, my questions: Why fan speed curve so sharp? Can I make it smoother? (i.e., increase fan speed more evenly).

[LeonWaksman]

The fan speed increase with each degree rise is controlled by the value of Duty Cycle Increment. In your custom setting, after reaching the Minimum Temperature of 75 DEG, the fan will increase speed by 4%/1DEG C. So, since your Minimum Duty Cycle is set to 20 %, when the CPU temperature reaches 95 DEG C, the fan will reach 100 % speed (Delta temperature 20 DEG C x 4% = 80%; 20% + 80% = 100%).

I would try to change the Minimum Temperature of 80 DEG and the Minimum Duty Cycle is set to 30 %. With those settings in normal use you will have still quiet NUC, less sensitive for triggering the FAN, while still getting 100 % fan speed at 97.5 DEG C.

Leon

[Konstantin]

Thanks! I will try.

[DKoma3]

Hello guys, Leon

The problem with this fan speed regulation, it has a high delay. When I run some cpu tests, temperature raise up to 80 and fan speed controller still do not notice (some smoothing/filtering of measured temperature as input to our rpm formula?) Then suddenly, it wake up (sometime even after 10s) and fan goes straigh 100% - where it is extremely loud.

Guys, are you sure also Windows does not play some role here? In power settings, you can choose active or passive aproach.

I have 25% as minimum, min temp 55, step 2%

[LeonWaksman]

Hello @DKoma3​ ,

1. You may try the following settings (pay attention for the secondary temperature sensor also): Fan Control Mode to Custom, Primary Temperature Sensor to Processor, Fan Off Capability - uncheck/disabled, Minimum Temperature to 85, Minimum Duty Cycle to 40, Duty Cycle Increment to 6, Secondary Temperature Sensor to Memory, Minimum Temperature to 60, Minimum Duty Cycle to 40, Duty Cycle Increment to 6.
2. You may want also to disable Turbo Bust Technology in the Performance tab. This will decrease the fan fluctuation as result of CPU frequency change with very minor effect on performance.
3. Press F10 confirmed by "Y" to save settings and exit from bios.
4. FYI, this is correct that when the CPU reaches temperature 90-95 Deg C, the blower should be at 100% RPM. Still, the temperature should go down quickly. Are the air inlets and the blower and cooling solution clean from dust?

Leon