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Question

Introduction:

 

Most ThinkPad models do not provide the operating system (or the user) the ability to set the fan speed directly (e.g. in rounds per minute) or in a fine-grained way (e.g. as a percentage of maximum speed). Instead, there are "fan speed levels", usually 9 levels (level 0 through level 7 as well as the level "disengaged"). For each level, a particular fan speed is defined and the Embedded Controller tries to achieve this particular fan speed by measuring the fan speed and adjusting the electrical properties of the fan (e.g. voltage or pulse length or something like this).

 

The fan noise problem:

 

Every time the internal temperature sensor reaches 50 °C or so, the fan starts with about 1900 rounds/minute and then quickly goes to about 2737 rounds/minute, where it is loud. Then it takes about 20 seconds, the temperature drops to 45 °C, then the fan is switched off. Then, after maybe other 30 seconds, the cycle repeats and the fan is switched on again, ...

There are major problems with this behaviour, because:

  • The fan is not running continously, but pulsating.
  • The fan is running at level 1 at a much higher speed than needed, creating unnecessary noise.

 

I have measured the individual fan speeds for individual fan speed levels:


The fan speeds at different levels are as follows:

  • Level 0: 0 rounds/minute
  • Level 1: 2737 rounds/minute
  • Level 2: 2944 rounds/minute
  • Level 3: 3033 rounds/minute
  • Level 4: 3074 rounds/minute
  • Level 5: 3597 rounds/minute
  • Level 6: 3773 rounds/minute
  • Level 7: 3773 rounds/minute
  • Level disengaged: 4754 rounds/minute

 

Solution draft:


A minimum solution to the problem above would be introducing another fan speed level between 0 rounds/minute and 2737 rounds/minute, with about 1900 rounds/minute. The reason this makes a difference is that there is a fundamental difference between laminar flow and turbulent flow, where the laminar flow makes nearly no noise and the turbulent flow makes a lot of noise. (Whether an airflow is laminar or turbulent is easiest influencable by affecting its speed.)

As you can see on the observed mapping from fan speed level to fan speed, level 6 and level 7 map to the same speed.

 

Thus, no particular fan speed would be lost if the mapping would be changed to the following:

  • Level 0: 0 rounds/minute
  • Level 1: 1900 rounds/minute
  • Level 2: 2737 rounds/minute
  • Level 3: 2944 rounds/minute
  • Level 4: 3033 rounds/minute
  • Level 5: 3074 rounds/minute
  • Level 6: 3597 rounds/minute
  • Level 7: 3773 rounds/minute
  • Level disengaged: 4754 rounds/minute

 

Solution implementation by user is impossible:


The problem, however, is that, while a user can decide which fan speed level should be active at a particular time, the user cannot decide which fan speed should actually be achieved for a particular level. Thus, the user can either decide to have 0 rounds/minute (which is not particularly sustainable, because the equipment becomes hotter and hotter) or to have 2737 rounds/minute (which is not particularly sustainable either, because both the user and other people arund the user's Lenovo computer are distracted from work).

 

The mapping from fan speed level to fan speed is actually stored in the Embedded Controller Programm ("ECP"). This Embedded Controller Programm is freely changeable or configurable by the user. Only Lenovo has the source code to this Embedded Controller Programm, and actually only Lenovo may know how to disassemble such a binary Embedded Controller Program in case the user wanted to change it. Thus, even advanced users cannot fix this problem by fixing it where it should be fixed.

 

It should be noted that, because fan speed is a long lasting issue at Lenovo, a third party has been even developed an after-market hardware solution: TPFC. However, this solution probably voids the warranty, and it work arounds the problem at the wrong place, and it costs time and money and effort to actually install it.

 

 

 

 

Answer

In light of this issue, our engineers has been working hard to ensure to addres this accordingly. A new BIOS v2.54 has be released to the public to address the fan noise issue on this system when docked or undocked. You are advised to download the BIOS from the link below or by going to the Lenovo support site http://support.lenovo.com.

 

http://download.lenovo.com/ibmdl/pub/pc/pccbbs/mobiles/g4uj17us.exe

 

A detail list of the change logs can be found below.

 

CHANGES IN THIS RELEASE
  Version 2.54

[Important updates]
  Nothing.

[New functions or enhancements]
- Improved the fan noise when docked.

[Problem fixes]
- Fixed an issue where the help message about the Restart menu in ThinkPad Setup
  was inccorrect.
- Fixed an issue where the integrated Bluetooth device was not available when
  "USB UEFI BIOS support" was disabled in ThinkPad Setup.
- Fixed an issue where some settings were not updated immediately after loading
  default settings in ThinkPad Setup.
- Fixed an issue where some unexpected characters might be shown on the left-top
  on screen when a diagnostic splash screen was displayed.
- Fixed an issue where the computer might not enter standby state of the 30day
  standby at the first boot just after executing Load Default Settings in
  ThinkPad Setup.

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Comments
xtaski

I have the same exact problem in my T420 and have upgraded to latest bios 1.48.  No change.  Why is there no solution.  Apparently this has been a  problem for a very long time.