continuous running of fans (overheating) on Dell XPS 15 9560

My guess is that something has been done with the graphics drivers. Until this is fixed, an intermediate solution is to switch to onboard graphics (see here). In short, run nvidia-settings and select PRIME Profiles and use Intel (Power Saving Mode).

This is the image from the link:

You should see the change in Details

Install i8kutils:

sudo apt install i8kutils

Follow the guide How to solve Dell laptops fan issues in Ubuntu.

I have the same laptop and had the same issue in Ubuntu 18.04 and then Ubuntu 20.04. Basically, it's caused by the Nvidia drivers.

If you are only doing non graphical intensive tasks on your laptop:

• run NVIDIA X Server Settings then under PRIME profiles switch to intel (power saving mode).

** /!\ NEXT SOLUTION IS AT YOUR OWN RISK /!\ **

Else, install greenwithenvy (https://gitlab.com/leinardi/gwe). To be able to access the full capabilities of that software, you will have to enable the Cool Bits Option to a certain value (https://wiki.archlinux.org/index.php/NVIDIA/Tips_and_tricks#Enabling_overclocking). To do that, I did :

sudo gedit /usr/share/X11/xorg.conf.d/10-nvidia.conf

then I added the following line

Option "Coolbits" "29"

after the Driver Nvidia line. (What that guy did --> https://ubuntuforums.org/showthread.php?t=2435095)

Once you modified that, restart your computer and pray for your GUI to not be broken... If that were the case, follow that guide: https://itsfoss.com/fix-ubuntu-freezing/ and rollback what you just did. Find another way, can't help you there. Sorry.

If that worked, you should be able to access the fan options and other overclocking stuff greenwithenvy allows you to do. You can tweak the fan behaviour, try the custom one they propose, it's good. Regarding the overclock profile, create a new one and assign the lowest negative values allowed for your GPU Offset and Mem Offset. I use -200 and -1000. Yes, you will loose a bit in term of performance but on the other hand, your laptop wont overheat for nothing, or worse, turn itself off...

Note that now you can also use Nvidia X Server Settings to underclock your GPU using Powermizer.

Hope that helps.