Ubuntu 18.04 LTS heating issue

It doesn't have anything to do with Ubuntu itself - I have a laptop and it runs just fine without any problems. To solve the problem please share your specifications and share your logs - if you're new with Ubuntu and/or Linux please use Gnome Logs and try to catch if there's any particular log related to overheating - CPU/GPU etc.

What easily could happen is that the hardware you use isn't fully supported and for example it cannot start system fans if any (MB drivers).

Also instead of TLP you can use other existing tools -you can check this good new Linux user article here. In this case TLP has to be removed first:

sudo apt-get purge tlp
sudo apt-get purge tlp-rdw

Regardless that try to install Psensor if the laptop gives you enough time. It will show you what exactly is being overheated. It will need some dependencies to be installed and configure first as per this article here.

After that please post the results you have.

P.S. I'm a new Linux user too as it's (as Linux in general) way more powerful the W, but with great power comes great responsibility:) As it works differently from W it takes some time to understand it. I had to reinstall it a couple of times when I had simple problems in the past, since that, reading and getting more experience I've solved every single problem without much troubles and spending a lot of time. Just do not give up so easy it worth the efforts at the end.

I had overheating issues with Ubuntu on my home laptop. The curious thing is that the issue showed up just with user ids used by my family members while with my personal uid I have no problem. I found that all users but me had an "unknown display" enabled other than the builtin one. Disabling the "unknown display" solved the issue. Maybe it was just my case, however I'd suggest a quick check.

Under volting helps a lot when there is over heating (and by lot I mean A LOT). To be on a safer side, manufacturers supply higher voltage than required to the CPU (which causes heating), as at lower voltages CPU doesn't work properly under stress. Under volting is completely safe. It will not void your warranty what so ever.

Try intel-undervolt from here.

Here is a guide to help you along.

Some terms in the guide might be depricated. Refer the first link for the deprecated terms.

As of selecting the offset, I use undervolt 0 'CPU' -130 in the /etc/intel-undervolt.conf file. As a beginner I would suggest you to stick to undervolting the CPU only.

To find the correct offset (unique to each CPU piece. Same CPU but on different computer could have different ideal offset) slowly lower the offset by small values (I used 10), and at the point where your PC crashes, is the threshold. And set the final value to threshold - 10. In my case it crashed at 140 so I set is to 130.

The only down side is that you will have to apply the settings on every boot. I have created an alias with alias us='sudo intel-undervolt apply && sudo tlp start'. So I just have to type us in the terminal on a boot, and then I am good to go.

Note: the crashing of PC to calculate the offset is completely safe. It will not damage you hardware whatsoever.

Note: Any Intel CPU can go to -125 at least, above that comes the difficult part. If you want to take it to the limit, then only try increasing it step by step. Other wise -125 will work just fine for any Intel CPU.