Comment 72 for bug 1768976

UPDATE:

Solved by disabling bluetooth in bios according to:

https://askubuntu.com/questions/1028883/ubuntu-18-04-systemd-udevd-uses-high-cpu-conflict-with-wifi

It is silent and cool now.

Under the link you can find guys saying that this systemd-udevd 100% cpu usage is because of the dell bluetooth. Others might have similar issues with this. There is a probable solution here too if you want to use your bluetooth too. I didn't try it though.

In summary: blacklisting nouveau, installing nvidia driver and disabling bluetooth solved the overheat problem for me.

I feel this is a workaround though, and linux shouldn't overheat in any case.