Comment 11 for bug 1800446

I have the same issue on an acer vn7-592g and Ubuntu 18.10. I temporarily fixed by editing thermald config in /etc/thermald/thermal-cpu-cdev-order.xml to deactivate most cooling methods (guess work as the documentation for it is almost none existent)

<CoolingDeviceOrder>
 <!-- Specify Cooling device order -->
 <CoolingDevice>rapl_controller</CoolingDevice>
 <!--<CoolingDevice>intel_pstate</CoolingDevice> -->
 <!--<CoolingDevice>intel_powerclamp</CoolingDevice> -->
 <!--<CoolingDevice>cpufreq</CoolingDevice>-->
 <!--<CoolingDevice>Processor</CoolingDevice> -->
</CoolingDeviceOrder>

On my setup only "rapl_controller" seems to work. "cpufreq" has no effect (might have something to do with my TLP config)

"intel_pstate", "intel_powerclamp" and "Processor" never stop throttling once the temperature limit is reached.

If needed, throttling can be reset without rebooting by:
"intel_pstate" --> sudo tlp start (you probably don't need tlp but I don't know the underlying command that makes it work)
"intel_powerclamp" --> sudo rmmod intel_powerclamp (https://askubuntu.com/questions/457252/intel-powerclamp-start-stop-forced-idle-injection)
"Processor" --> no idea, can't even find documentation on what it actually does