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2 Posts

06-15-2021

France

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Strange fan behaviour (T14 Gen 2i, T420s)

2021-06-22, 10:52 AM

I've just bought a T14 Gen 2i to replace my good old T420s and I observe that the behaviour of the fan still looks bad, I'd even say worse. As a workaround, Linux gives the ability to control the fan from software, what I've done from the beginning for my T420s and what I continue to do for the T14 (I wrote my own program to do that).

 

I assume that what controls the fan by default is the EC. If I'm wrong here, sorry for the mistake throughout this post, but it changes nothing.

Also for reference, here are the possible fan speeds for the T14:

  • normal mode: 0, 2290, 2780, 2960, 3360, 3860, 4290
  • full-speed: 6000

Here is a list of issues:

 

1. Undersized fan

 

Both i5-2520m (T420s) and i7-1165G7 (T14G2) can heat a lot, with a first limit of 86°C for the i5 and ... 100°C (?!) for the i7, and they can reach their limits quickly.

 

I suppose Lenovo didn't put a more powerful fan because the laptops would not be as slim as they are. But given the chosen fans, the behaviour could be better.

 

Here, what I wonder most is why the EC never takes advantage of full-speed mode. Maybe the fan does not like being in such mode for too long so I also played on CPU turbo to limit overheating.

 

What I programmed on my T420s is:

  • disable CPU turbo when exceeding 80°C, reenable it if below 75°C
  • put fan in full speed when exceeding 86°C, which rarely happens anyway when turbo is disabled

The above rules for the T420s worked well and they were useful because the i5 does not seem to be good at limiting overheating by itself.

 

On the T14, I don't really know what to program yet. Lenovo seems anyway to rely on the fact that the CPU reduces its frequency automatically, maintaining the temperature between 90 & 95.

 

2. [T14 only] fan speeds up very slowly to the requested speed

 

It takes 13s to go from 2290 to 4290 rpm. Far too slow for a CPU whose temp can rise from 35°C to more than 90°C in a few seconds. That's frightening.

 

3. Too fast when idle

 

On the other side, I don't see the purpose of trying to cool the laptop so much. First because it does not seem great for the hardware that the temperature varies so much. And below some temp, the fan is pretty useless anyway, aging quickly with much noise.

 

On my T420s, the fan would be noisy. With my software, the fan can be off most of the time, and running at the lowest speed from time to time.

 

Well, the EC is actually strange. At the beginning, it can be relatively quiet. As soon as the laptop has exceeded some temp, the EC starts cooling more aggressively. I don't understand the logic.

 

1-3. Summary of the above points

 

On both laptops, and I guess it's similar for all thinkpads for many years:

  • fan too fast at low temps
  • fan too slow at high temps

4. [T14 only] fan running when sleeping

 

First of all, unfortunately, there's no more deep sleep (S3) on the Gen 2. I have the feeling that S3 would consume less battery that s2idle, am I wrong ?

 

Anyway, what I find strange here is that fan is still controlled as if the laptop didn't sleep. This makes no sense for me because when sleeping, the laptop consumes little enough for heat to disperse passively. Some bad consequences:

  • The fan would also use battery for nothing.
  • I know it's not great to be in front of a screen before going to sleep but I don't want to wait such a long time for the noise to stop.

Overall, I care a lot about the health of both my hears & hardware. I hope the way I control the fan does not damage any component prematurely. My T420s lasted for a long time.

 

If I'm wrong, I'm interested to know where. Otherwise, I hope to see improvements in a next firmware update.

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6571 Posts

08-02-2018

Philippines

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Re:Strange fan behaviour (T14 Gen 2i, T420s)

2021-06-23, 9:57 AM

Hi jmuchemb!


Welcome to community forums

 

 

Can you provide the MTM of the T14 Gen 2 variant that you are referring to? And also include the OS version and the BIOS version you are currently running on?

 


Let us know.

 

 

 

Jwes_Lenovo



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2 Posts

06-15-2021

France

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Re:Strange fan behaviour (T14 Gen 2i, T420s)

2021-06-23, 10:31 AM

MTM: 20W0004MFR

BIOS: N34ET34W (EC: N34HT32W)

OS: Linux 5.12.9

 

Oh, there's a newer BIOS. I don't understand all the changelog but it does not seem to improve the fan. The change « Fix FLOCKDN is not set after S3 resume » is strange because there's no S3.

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Re:Strange fan behaviour (T14 Gen 2i, T420s)

2021-06-23, 17:26 PM

I see. Recommended Distro here for your model:
https://support.lenovo.com/us/en/solutions/pd031426-linux-for-personal-systems


 
Perhaps you can try it to see if you have the same issue with the fan behavior.

 

 

 

Jwes_Lenovo



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7 Posts

06-17-2021

Germany

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Re:Strange fan behaviour (T14 Gen 2i, T420s)

2021-08-06, 12:37 PM

@ jmuchemb wrote:

3. Too fast when idle

 

On the other side, I don't see the purpose of trying to cool the laptop so much. First because it does not seem great for the hardware that the temperature varies so much. And below some temp, the fan is pretty useless anyway, aging quickly with much noise.

 

On my T420s, the fan would be noisy. With my software, the fan can be off most of the time, and running at the lowest speed from time to time.

 

Well, the EC is actually strange. At the beginning, it can be relatively quiet. As soon as the laptop has exceeded some temp, the EC starts cooling more aggressively. I don't understand the logic.

 

 

In particular, I have this same issue with my T15 Gen2 20W4003WGE (also with i7-1165G7).

At minimum load or idle, the fan runs permanently at >3600 RPM which results in unacceptable noise.

I have written down my experiences in this post (unfortunately in German).

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6571 Posts

08-02-2018

Philippines

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Re:Strange fan behaviour (T14 Gen 2i, T420s)

2021-08-06, 21:37 PM


Perhaps you also check the support site on any available BIOS recently added to try on yours.

 

I hope we do not misdirect the original poster's intention so starting a fresh topic specific to your MTM and issue may be better.

 

 


Jwes_Lenovo



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16 Posts

07-15-2021

Russian Federation

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Re:Strange fan behaviour (T14 Gen 2i, T420s)

2021-08-07, 6:36 AM

@ jmuchemb wrote:

I've just bought a T14 Gen 2i to replace my good old T420s and I observe that the behaviour of the fan still looks bad, I'd even say worse. As a workaround, Linux gives the ability to control the fan from software, what I've done from the beginning for my T420s and what I continue to do for the T14 (I wrote my own program to do that).

 

Well, the EC is actually strange. At the beginning, it can be relatively quiet. As soon as the laptop has exceeded some temp, the EC starts cooling more aggressively. I don't understand the logic.

 

thanks for the informative summary! interesting.

 

There's a relevant topic on the issue (exsessive heat/noise), seems to apply to most Gen2 devices especially with i7-1165G7, (and OP runs linux too):

 

T15g g2 - 60°C CPU idle temperature and fans spinning continuously (Debian)

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6571 Posts

08-02-2018

Philippines

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  • Posts: 6571
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  • Message 8 of 8

Re:Strange fan behaviour (T14 Gen 2i, T420s)

2021-08-10, 21:56 PM


For Windows machines, there is the Lenovo Intelligent Thermal Solution Driver offered.

https://pcsupport.lenovo.com/us/en/products/laptops-and-netbooks/thinkpad-p-series-laptops/thinkpad-p43s-type-20rh-20rj/downloads/ds502230-lenovo-intelligent-thermal-solution-driver-for-windows-10-64-bit-thinkpad


 For those of different Distro’s perhaps better to have a post over that board so the fellow enthusiasts can suggest specifics.

 


Jwes_Lenovo



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