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  • Registered: ‎01-07-2012
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Re: T420s Fan noise Issue

2012-05-19, 1:11 AM

@Mark_Lenovo Hey Mark! We're still waiting for an update!


2 months ago I tweeted a question to the official @lenovo twitter account, asking if you were ever going to fix this issue. The @lenovoforums account (which I understand you, Mark, is in charge of?) answered "we've addressed many of the cases through BIOS update. Still some remain. Need a sample that isn't fixed by bios"


So my question is: Why the heck aren't you cooperating with all the people in this thread who're having problems???



Anyway here's an interesting observation I made yesterday. I met another guy with a t420s that didn't make that annoying high pitched noise, but more like a deep humming, even though his machine was also spinning away at 4000RPM. I'm fine with the fan spinning at 4K if it's just not making that annoying whiny noise. Could it be that some of the fans are just more noisy that others? And the sound problem could be solved by replacing the fan? Has anyone had success replacing the fan?


And another question.

On this page there's listed two different part numbers for the fan part (and another two numbers for optimus fans). What is the difference? One is labeled 'not to be replaced by user' and the other is not?


21115 Posts


Australia, Melbourne

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  • Message 1102 of 1217

Re: T420s Fan noise Issue

2012-05-19, 9:29 AM
Lenovo usually uses two companies for the fan.

In the past Fukuwara and Toshiba are the major manufacturer for ThinkPad laptop fan. But nowadays, Panasonic fans are also used.

So check which fan you have, i think there should be a sticker on the fan itself, and check which fan that the other person has. You can reach the fan by taking off the keyboard.

Jin Li

May this year, be the year of 'DO'!

I am a volunteer, and not a paid staff of Lenovo or Microsoft

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  • Message 1103 of 1217

Re: T420s Fan noise Issue

2012-05-19, 15:49 PM
For what it's worth, my first T420s used an AVC BATA0507R5U fan. When they replaced the fan, it was also an AVC.

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  • Message 1104 of 1217

Re: T420s Fan noise Issue

2012-05-21, 22:29 PM

@ LinYu & pleon: Thank you for the hint.

Unfortunately there is no improvement of the high spinning fan behaviour after uninstalling the display driver.


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  • Message 1105 of 1217

Re: T420s Fan noise Issue

2012-05-22, 12:02 PM
Well, strange, i made test on 2 T420s devices and it helped on both of them.
Lenovo T440s, 20AQ0067MC, Windows 8.1 Pro x64 UEFI, Samsung 840 EVO SSD 250 GB, 8 GB RAM
Lenovo T430s, 2356LQG, Windows 8.1 Pro x64 UEFI, Intel 520 SSD 180 GB, 8 GB RAM
Lenovo T420s, 4171-6SG, Windows 8 Pro x64 UEFI, Intel 320 SSD 120 GB, 8 GB RAM
Lenovo T400s, 2808-CYG, Windows 7 Ultimate x64

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  • Registered: ‎05-26-2012
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  • Message 1106 of 1217

Re: T420s Fan noise Issue

2012-05-26, 1:21 AM



Finally, my t420s (i5, 256ssd, 8gb) is quiet after uninstalling of "Lenovo - Display - ThinkPad Display 1600x900" driver. It was really annoying.




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  • Message 1107 of 1217

Re: T420s Fan noise Issue

2012-05-26, 7:18 AM


So, in order to be totally clear, I would like you to please confirm this for me:


Is it accurate to say that you simply uninstalled "Lenovo - Display - ThinkPad Display 1600x900", did nothing else, and your fan is now working normally, with no noise.


Is this so?


Thanks in advance.


Lin Yu


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  • Message 1108 of 1217

Re: T420s Fan noise Issue

2012-05-26, 18:17 PM

I uninstalled the display driver last night, and have noticed a major reduction in fan noise. It definitely seems to be spinning up less now. I'm still getting all the random electrical noises coming from inside my laptop though.


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Austin, Texas

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  • Message 1109 of 1217

Re: T420s Fan noise Issue

2012-05-26, 22:18 PM

I came across the following Youtube vid http://www.youtube.com/watch?v=DiixRw1aeI8If

If the high-pitched noises that you (alvoha) describe are very similar to the one in the video, I have some clues based on my experience as a motor circuit designer.


The cooling fan is typically (almost always) driven by a BLDC motor. BLDC motors Inherently do not have commutators, so they require a electrical swithing action of the stator windings to spin the rotor. This electrical switching action often produces undesired noises that you describe. It is caused by the vibrations of the conductors in the windings and the laminated plates.


To reduce the noise, we often use "switching hysterisis" by adding additional energy dissipator like resistor or diode. Some BLDC motor produce more acoustic emissions due to poor winding constructions. I know this because I design this kind of motor control circuitry and test it in a regular basis. 


Another possible source of the high-piched noises is from the BLCD driver which varies the supply voltage of the motor to control the speed of the motor. The motor driver is based on the switching action of MOSFET transistors, and the switching action often cuases undesired high-frequency harmonics and the high-pitched acoustic emissions via the motor winding. If you want to know more about how to control the BLDC motor, read at  http://cache.freescale.com/files/microcontrollers/doc/white_paper/QD4DCFAN.pdf


My guesses of the fan noise issue (high-pitched whine) are


1. possible downgrade of the fan assembly : IMO when Lenovo first designed the fan control circuit, I don't think they okayed the mass production with those kind of fan noise issues unresolved. From my experience, some motors of even the same model are more prone to those acoustic noises especially excited by the switching power source with distorted harmonics.  


2. poor switching hysterisis : I read in this forum that some people reported that Lenovo replaced the motherboard as well when they requested the repairs. My guess is that the motor driver circuit is embbed in the motherboard and the switching hysterisis problem can be corrected only by the circuit modification (i.e. new motherboard).










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  • Message 1110 of 1217

Re: T420s Fan noise Issue

2012-05-27, 1:57 AM

Hmm, I had BIOS ver. 1.31 and downgraded first to 1.25 but the problem was still present. With 1.28 it seems to work.

It is now quiet (2000rpm)  in only 5-10sec after win7 start and also in the idle state.



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