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147 Posts

12-08-2019

United States of America

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Re: Yoga C940 4k - Fan runs constantly

2020-01-02, 15:48 PM
If only the Surface Laptop 3 had Thunderbolt and was a 2 in 1 this option would have been gold. But alas, only other 2 in 1's are either small 13 inch screens or have really old processors :/
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4 Posts

01-03-2020

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Re: Yoga C940 4k - Fan runs constantly

2020-01-03, 21:38 PM

bought the c940 1080p version on thxgiving and kept on monitor this thread. Tried everything (disable intelligent cooling, quiet mode, passive mode for battery, lower % of power management) but throttlestop (have issue installing), still the fan runs constantly with high pitch. Was planning to replace the laptop but the policy is different from holiday return. Therefore, good bye lenovo, i am returning this laptop.

too bad, it is a decent laptop if it has no fan noise.

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147 Posts

12-08-2019

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Re: Yoga C940 4k - Fan runs constantly

2020-01-03, 21:54 PM
what was the issue installing throttlestop? if it's an error that says "mc140..." or something, you just need to install something from Microsoft's site. Google it and it appears instant.
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4 Posts

01-03-2020

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Re: Yoga C940 4k - Fan runs constantly

2020-01-03, 22:37 PM

Hi Liopag2,

Thanks, your reply triggered me to re-read the instructions online, i met mfc120u.dll is missing and I only installed the vcredist_x64.exe. Just installed vcredist_x86.exe as well and could installed throttlestop. 

 

Undervolt to -80mv, still fan is on constantly when temp is below 51 degree celcius and cpu around 19%.

 

 

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21 Posts

12-24-2018

United States of America

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Re: Yoga C940 4k - Fan runs constantly

2020-01-04, 21:22 PM

Guys, today I removed the lid of the c940 and run some benchmarks at full fan speed. I can confirm the high pitch whistle noise comes from the vents, not the fan itself, because without the lid it doesn't make the whistle noise. So now I'm thinking maybe doing a mod and do some holes in the lid :D

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147 Posts

12-08-2019

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Re: Yoga C940 4k - Fan runs constantly

2020-01-04, 21:28 PM
Previously I had read that if you sealed part of the right bottom portion of the vents you can get the coil whine to stop by a large margin. I have light coil whine on mine and can confirm it reduces it somewhat of a margin.
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4 Posts

01-03-2020

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Re: Yoga C940 4k - Fan runs constantly

2020-01-04, 23:43 PM

I tried tape some part of the vent, it is working. I can no longer hearing the high pitch noise. the fan sound I do not care about as it does not hurt my ears no more. temperture does not seems to raise so I think the amount of hole i taped is good.

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2 Posts

01-06-2020

Malaysia

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Re: Yoga C940 4k - Fan runs constantly

2020-01-06, 3:22 AM

I've just ordered the C940 (4K, i7, 16gb, 512gb SSD) and I wanna know is there any way to solve the fan issue if I were to encounter it? I hope my unit won't have this problem but I'm kinda worried since a lot of people complain about it but Ive also seen posts by people where they did not have this problem which is very strange. 

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10 Posts

12-02-2019

Australia

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Re: Yoga C940 4k - Fan runs constantly

2020-01-06, 10:28 AM

The short answer is nobody here can predict the level of fan noise you will have on your specific C940, or whether you will be able to resolve it.  It really depends on your usage, and your expectations.   

l have an identical config to your order, and have not experienced any issues with fan noise - and have sensitive hearing.  I don't doubt others are having issues, but you are seeing a relatively small subset of owners commenting here, so it would not appear to impact everybody.  I'm not hearing any coil whine either.   

 

My C940s fans rarely fire up for a number of reasons:

Its 90% of the time running on battery.

It is not used throughout the day as a business machine.

I don't run much beyond a web browser, email, and content viewing the majority of the time. 

 

When my fans DO fire up, the fan whine some are noting (which would be REALLY irritating), has not been apparent on my C940.  The comments about fan vent taping to get rid of the whine may be applicable to some - but not all.   

Battery life also seems fine compared to my last (well current..) laptop, probably as I dont have the screen on full brightness, and dont really push the processor too hard.  For me even 3 hours would be fine for after work usage,  the 6+ it is delivering is great. 

 

 

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16 Posts

01-02-2020

Germany

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Re: Yoga C940 4k - Fan runs constantly

2020-01-06, 20:56 PM

FHD / i7 / 1TB / 16GB

 

I posted about the "tape mod" since a few months on several youtube vids. It worked out great for me.

 

See also: https://www.reddit.com/r/Lenovo/comments/egxkta/c940_yoga_possible_fix_for_the_high_pitched_fan/

 

Sorry for the bad pics, it was late and i was quite tired (of this **bleep**...)...

 

I recently repasted the CPU/APU and my temps dropped for around 5° Celcius. Only problem that occured after i removed the thermal module (heatpipes and fans) was that the high pitched noise became much worse (it now also came from the left fan....).

 

I reseated / repostioned the fans again and now the high pitched fan noise of the left fan is nearly gone, albeit before my repaste the left fan was completely silent...

 

So basically now i have quite good temps, and the high pitched noise on the right fan is nearly gone (90%) and on the left fan it is totally acceptable (i am sensitive to this and young enough (< 30) to hear this). Luckly the left fan only starts at very heavy workloads and constant temps above ~ 65°, so in my case it is off for around 90% of the time.

 

My CPU/APU is undervolted at -85mv via throttestop and stable at CPU only tasks. For gaming or any task that heavily uses the iGPU (i don't mean 4K HDR YouTube Vids) i have to lower it to -65mv. Since i basically never use the iGPU it stays at -85mv.

 

I use it in 60/40 desktop/mobile setup. Most of the time i have my 192 Speed Shift Throttlestop profile activated and it works just fine. The right fan rarely activates, my temps stay around 40-50° (desktop/loading mode). At around constant 52/53° the right fan kicks in. So in summer it will definitely be worse... here in germany almost nobody as AC... currently my room temperature is around 21°.

 

The windows power profile and Lenovo Vantage Power settings stays at "best performance". I don't notice any difference if i have throttlestop running at the same time (192 Speed Shift). For gaming/best performance though you should at least have the Lenovo Vantage setting at best performance because otherwise it will limit the tpd/wattage of the CPU and maybe add a throttlestop setting with Speed Shift 0. I don't think the windows power settings does anything different than changing the speed shift. But i am not sure about this, found no good info about this topic.

 

If somebody knows a better mod for the high pitched noise please let us know. I definitely comes from the airflow / air inlets and not from the fans itself.

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