Mini S13 Smart Fan ignores PWM curve, runs full speed or oscillates

S13MiniOwner

On the Beelink Mini S13 (Intel N series), the CPU Smart Fan Mode does not follow the PWM curve. Instead of gradual fan control, the fan behaves like an on off switch and runs at full speed or rapidly oscillates. This is already visible in BIOS and is not related to the operating system.

System
Model: Beelink Mini S13
OS: Ubuntu Server latest LTS
BIOS: Aptio Setup Utility v2.22.1293, factory latest
Usage: 24/7 low power home server

What was tested
Advanced, Thermal Configuration, CPU Smart Fan Mode
Automatic mode with multiple combinations:
Fan off 40 to 50 °C
Fan start 50 to 60 °C
Full speed 85 to 90 °C
Start PWM 30 to 40 percent
PWM slope 1 to 2

Optimized Defaults were loaded once, settings were re entered, and saved with F4.

Observed behavior
Fan immediately runs at 100 percent after boot or reboot.
Fan either stays at full speed or oscillates between 0 and 100 percent.
No stable intermediate RPM.
Behavior visible in BIOS before Linux starts.
Linux sensors shows normal idle temperatures around 40 to 60 °C.

Only Manual Mode with fixed values allows reducing fan speed.

Questions
1. Can you please confirm whether this is a known Mini S13 BIOS or EC Smart Fan behavior?
2. Are there recommended Smart Fan settings for a quiet, always on Mini S13 setup?
3. Is there a newer BIOS or EC firmware that improves fan control?
4. Is there an official workaround or guidance for Linux based fan control?

I really like the Mini S13 for its size, efficiency, and performance. Low noise was an important reason for choosing it, so any guidance, firmware update, or recommended configuration would be greatly appreciated. I’m happy to provide videos, screenshots, logs, or any other information needed to help reproduce and resolve the issue.

Beelink CS-June

S13MiniOwner

Hello there,

Sorry for the trouble.

Could you please send us a picture of SN code at the bottom of machine ?

Please repeatedly press delete key as soon as you turn on the PC, go to BIOS. Please send us a picture of the Main page, we will check if you need to update the BIOS.

This is a tutorial on adjusting the fan speed in the BIOS： https://buildin.ai/lizong/28aabe34-263d-415e-b016-292f765125aa

The fan problem you reported is not a known issue.

We are sorry that we don`t have official workaround or guidance for Linux based fan control.

Have a nice day~

S13MiniOwner

I have tested the Smart Fan settings from the link you provided. Unfortunately, they do not work as intended on my unit and lead to the same behavior described in my original message. The fan still runs at full speed or oscillates instead of following a gradual PWM curve.

One detail came to my attention that I would like to point out. In your screenshot, the BIOS shows both CPU Smart Fan Mode and System Smart Fan Mode, each with separate temperature limits, PWM values, and slope settings. On my Mini S13, however, only CPU Smart Fan Mode is present. The System Smart Fan Mode section is completely missing in my BIOS. Is this expected behavior, or could this option be hidden or dependent on a specific BIOS or EC version?

I have attached screenshots of my BIOS as well as the screenshot from your guide to illustrate this difference. The BIOS on my device has already been flashed and should be the newest available version. I have sent a photo of the device serial number and the bios serial number screenshot to you separately via private message.

I would also like to clarify that this behavior occurs directly inside the BIOS setup screen, immediately after power on, before any operating system starts. At that stage, Linux is not running and cannot influence fan behavior. For this reason, I suggest we focus on the BIOS or Embedded Controller fan control rather than the operating system.

At the moment, the only way to reduce fan noise on my device is by using Manual Mode with fixed values. Automatic Smart Fan Mode does not behave correctly.

Thank you for your support. Please let me know if you need any additional information, screenshots, or tests from my side.!
Image description

Beelink CS-June

S13MiniOwner

Hello there,

Regarding the issue you raised about the System Smart Fan Mode section option, we are asking the technical staff and we will contact you after getting a reply.

If the fan problem of the machine you reported is the same whether it is under Windows or Linux, we suggest that you can send the machine back for inspection.

May I ask if you would like to?

Or we can apply for a new fan for you to try to solve the problem.

This is our after-sales email: support-pc@bee-link.com

Have a nice day~

S13MiniOwner

I’m interested in solving the issue and would be open to options like replacing the fan or sending the machine in for inspection. However, since the fan can be regulated using the manual fan mode, I suspect the issue is not the fan itself but rather the fan controller or firmware, although I don’t have deep knowledge of the internal fan control logic.

That said, the Mini S13 is in daily 24/7 use, so sending it in for several weeks would be difficult for me at the moment.

Thanks for the update. I’ll wait for feedback from the technical team and hope this can be resolved at the BIOS or firmware level. If that doesn’t solve it, we can consider next steps.

Beelink CS-June

S13MiniOwner

Hello there,

Sorry for your waiting.

We have inquired with the technical staff and there is no updated version of the firmware available for the time being.

Technical personnel suggest that you can use this software to adjust SPEED FAN software to adjust the FAN SPEED: https://www.almico.com/sfdownload.php

Have a nice day~

S13MiniOwner

Thank you for checking with the technical team and for the update.

I understand that Linux itself is not officially supported, and that is acceptable for me. However, the issue I am experiencing is not related to Linux. The fan behavior occurs directly inside the BIOS, before any operating system loads. This indicates a BIOS or Embedded Controller fan control issue, which is part of the device firmware and should function correctly regardless of the operating system. I believe it is reasonable to expect working BIOS-level fan control on a new computer in 2025.

For this reason, the recommendation to use SpeedFan is not applicable in this case. SpeedFan is a Windows-only utility that was last updated in October 2015 and cannot influence fan behavior at the BIOS level. Since manual fan mode works reliably while automatic Smart Fan mode fails already at the firmware level, this strongly suggests an issue with the Smart Fan implementation rather than a problem that can be solved through software workarounds.

Even if SpeedFan were a modern and actively maintained application (Last modified on 30 oct 2015), relying on third-party OS-level software to compensate for non-functional BIOS fan control would not be an acceptable solution.

There is also an unresolved discrepancy between your reference BIOS screenshots and my device. Your examples show both CPU Smart Fan Mode and System Smart Fan Mode, while my Mini S13 BIOS only exposes CPU Smart Fan Mode. This difference may be directly related to the observed behavior and requires clarification.

At present, the only usable workaround is manual fan mode, which results in a system that is louder and less flexible than expected. Quiet and stable automatic fan control was a key reason for my purchase decision. Given the current situation and the lack of a firmware-level solution, I am considering returning the device, as it does not meet my expectations in this area.

I appreciate your efforts so far and would welcome either a proper BIOS or EC firmware solution or a clear confirmation that this behavior is a known limitation of the product.

Beelink CS-Rose

S13MiniOwner

Please send us a picture of SN number and BIOS main page.
So we would be able to know whether it is latest BIOS and send you files accordingly.
Here`s how to check your BIOS version:https://mega.nz/#F!yuISGa4I!s1bQQajKwnsEdzjqq4nopQ

S13MiniOwner

As mentioned above, this was already checked with your colleague. To quote June from a direct message:

“Your machine’s BIOS version should be the latest, you don’t need to update it.”

The BIOS version currently running on my Mini S13 is Aptio Setup Utility v2.22.1293. Unless a new BIOS has been released within the last few days, this is still the latest available version.

So at this point, the issue does not appear to be caused by an outdated BIOS.

What is still unclear is why my BIOS version lacks the System Smart Fan Mode shown in your guide screenshots, despite running the same reported BIOS version.

Beelink CS-Rose

S13MiniOwner

Sorry, the BIOS for the MINIS13 hasn’t been updated in the last few days.

Please contact our after-sales email: support-pc@bee-link.com

We can send you a new CPU fan.（Although June has already mentioned it）

S13MiniOwner

Thank you for the offer to send a new CPU fan. However, nobody has explained how a different fan would change the behavior I am seeing or why the fan itself would be the root cause of the issue. Because of this, I do not understand how replacing the fan would resolve the problem. I would be happy to receive some clarification on this.

I feel that I have already spent enough time trying to resolve this. I do not want to invest any more effort troubleshooting what seems to be a firmware limitation. To be honest, I am a bit disappointed that I still have not received any clarification as to why my BIOS lacks the System Smart Fan Mode.

Because of this, I have decided to return the Beelink Mini S13. It does not meet my expectations.

Thank you for your time and support.

Beelink CS-Rose

S13MiniOwner

We apologize for the poor experience. The fan not following the PWM curve may be due to a fan malfunction.

We will report the issue to the relevant department, and a tutorial on adjusting the fan speed of the MINI S13 N150 may be released later.