New BIOSes are much less agressive than the old ones, so this script is not needed anymore. It works just fine without.
The BIOS of Dell XPS 9560 frequently forgets to stop the fan when the fan is on lower speed and the CPU is cool enough. This is very annoying, as once the fan turns on, it rarely shuts down. There is a custom fan control daemon called i8k, but it turns off BIOS fan control which is very dangerous and suppors only 2 fan speeds.
Fortunately the fan immediately stops if "smbios-thermal-ctl --set-thermal-mode=quiet" command is run. But next time the CPU heats up, it starts over again. This tool is supposed to run the command periodically, but only in a given range of temperatures. There are some zones that results in oscillations (smbios-thermal-ctl turns off the fan for a second, and then it turns back on). On even higher temperatures, the command does nothing. So in order to avoid oscillations, we need a bit more sophisticated method than running smbios-thermal-ctl periodically.
Tested for 15 9560.
Run ./install.sh as root. This will set up the config file, the systemd scripts and the script itself.
You can try editing /etc/silent_xps.json if you run in some oscillation problems.
Python 3 for running the script, lm_sensors for reading the temperatures and libsmbios for smbios-thermal-ctl tool.