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Lendzian
Blue Screen Again
Posts: 3
Registered: ‎06-19-2018
Location: PL
Views: 10,652
Message 1 of 7

T480 - CPU temperature and fan speed under linux

Hi All,

Since a few days I am using T480 with Kubuntu 18.04.

When I use the laptop for web browsing and text edition (light use which should not consume too much resources), the CPU's temperature is always around 50 deg C, with the fan speed of around 3000 RPM (the average CPU usage is 6%). The MX150 GPU is disabled with NVIDIA X Server Settings. If the GPU is on, the temperature and fans speed is more or less the same.

 

Has anyone experienced similar CPU's temperatures regardless if it is windows or linux? Are such temperatures normal? The housing is pretty warm all the time.

The ambient temperature is around 24 deg C.

 

Best regards,

Lendzian

Lenovo Staff
Lenovo Staff
Posts: 6,063
Registered: ‎10-29-2009
Location: NC
Views: 10,566
Message 2 of 7

Re: T480 - CPU temperature and fan speed under linux

For linux, you need to change a BIOS setting.  Reboot and press F1 to enter BIOS setup.  In Config -> Thunderbolt menu, set "Thunderbolt BIOS Assist Mode" to "Enabled".  Then press F10 to save and exit.

Lendzian
Blue Screen Again
Posts: 3
Registered: ‎06-19-2018
Location: PL
Views: 10,542
Message 3 of 7

Re: T480 - CPU temperature and fan speed under linux

Thanks someotherguy for the help - it worked a bit, but I don't understand why Smiley Happy

Here some magick is happening after enabling this BIOS Assist Mode - the fan runs quite rarely, what makes the computer more pleasant to use in terms of noise. When the fan is silent, the CPU's temperature slowly increases to around 60 deg, what also affects the heat in the housing, and then the fan successively cools the CPU a bit and stops again - this is good.

Whatsurprises me is the fact, that the battery discharge rate is decreased from 15 W to 11 W after enabling the mode, which is contrary to the statement in this manual,  that the power consumption will be higher.

Slighty better battery discharge rate gives me a bit more precious minutes of battery life (which in my case unfortunately is still far from being "epic")

 

So again - thank you.

 

Would you have any clues that could help to decrease the battery discharge rate? The whole internet says that it is due to the fact, the GPU, instead of Intel's integrated graphics, is working continuously instead of occasionally.

 

And finally are the temperatures of 50 deg - 60 deg normal for T480 with MX150?

Best regards.

Lenovo Staff
Lenovo Staff
Posts: 6,063
Registered: ‎10-29-2009
Location: NC
Views: 10,536
Message 4 of 7

Re: T480 - CPU temperature and fan speed under linux

The manual is a bit confusing, and this situation is a bit complicated.  First, some background information.  Windows 10 1709 (and later) supports thunderbolt natively in the OS, so BIOS just needs to stay out of the way.  This is what BIOS Assist Mode = Disabled does.  This is the default setting since we ship Win10 1709 (or later) on these machines.

 

Windows 10 earlier than 1709, and most linux distributions as of today, don't support thunderbolt natively, so then BIOS has to do some of the work.  This is what BIOS Assist Mode = Enabled does.

 

The statement about increased power consumption refers to what happens if you set this Enabled but your OS actually supports thunderbolt native mode.  And similarly, if you set this to Disabled but your OS does not support thunderbolt native mode (which was your case).  So this BIOS setting has to match the capability of the OS, or else you end up wasting battery and making heat.

 

As for your other questions - I really have no idea.  It could be the linux driver for MX150 is not optimized, or there could be some background process that is eating CPU/GPU cycles and making heat.  I'm not a linux user, so I personally won't be able to help, but I suspect if you post in a linux forum you might get some ideas.  50-60° C at idle seems high to me so I think there must be something going on in the background.

 

 

Lendzian
Blue Screen Again
Posts: 3
Registered: ‎06-19-2018
Location: PL
Views: 10,520
Message 5 of 7

Re: T480 - CPU temperature and fan speed under linux

Ok, thank you.
Now I understand how it works and I'll try to explore the issue of linux's background processes, which unnecessarily heat up the CPU.

Best regards.

jordanzliu
Paper Tape
Posts: 2
Registered: ‎10-15-2018
Location: CA
Views: 7,770
Message 6 of 7

Re: T480 - CPU temperature and fan speed under linux

If you install nvidia proprietary drivers without properly blacklisting nouveau, sometimes nouveau will load and power up the dGPU. You can do this in a way that sticks between updates by editing /etc/default/grub to add

modprobe.blacklist=nvidia

to your kernel command line. This reduced my idle power from ~11w to ~5w.

sg91
Paper Tape
Posts: 2
Registered: ‎06-04-2019
Location: IT
Views: 3,922
Message 7 of 7

Re: T480 - CPU temperature and fan speed under linux

Hi Lendzian, i'm having the same problem since i'm using linux mint. Did you find out the reason for such unnecessarily heating?

I appreciate any suggestion

 

Best regards

 

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