Laptop CPU+GPU overheating after update to 18.04 LTS

Disable intel_pstate at boot by editing your grub configuration.

Open /etc/default/grub with your preferred text editor and locate the line that begins with:

GRUB_CMDLINE_LINUX_DEFAULT

And add intel_pstate=disable at the end of that string. Here's how mine looks after that:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash intel_pstate=disable"

Now, execute:

sudo update-grub

And reboot your laptop. That's it. It should work as smooth and cool as with 16.04.

Some additional information: intel_pstate governor seems to be buggy, or just plain stupid and unable to detect quick temperature raises and reduce the processor speed in consequence. It seems it'd just pray to Saint Cooling Device for it to keep the CPU below the shutdown threshold. In a desktop computer with a DC9 turbine like fan such leap of faith maybe justified, but in laptops with one small fan like my XPS13 it's better to be skeptic and leave those things to the good old ACPI (Atheist Configuration and Power Interface). At least until the intel_pstate governor grow some brains.

And the turbo boost is mostly useless. Chances are that you won't lose anything for having it disabled. That feature was useful in the days of monocore 32 bit processor, but not in the 64 bit multicore world we're living on right now.

I had issues with the i7-6500u as well.

Changes in the Linux kernel improved performance of Intel chips, with the side effect of causing thermal clamping on devices with a low thermal limit.

I found TLP helped a lot with toning down the behavior. Turning off turbo boost is another way to tame it. You can also set the fans to constantly run or come on at a lower temperature, which raises the thermal limit of the device.

tlp

As mentioned on this thread tlp works wonders for keeping system under control. It works with thermald, Intel Powerclamp, Battery vs AC for USB power, etc. Although highly configurable I've never had to change the configuration settings for a pleasant Out-Of-The-Box experience. Prior to using it I had all kinds of problems with an IvyBridge laptop overheating all the time. I have it on my new Skylake laptop and the fans NEVER run except when doing Ubuntu 16.04 LTS to 18.04 upgrade.

You can get a very detailed write-up with installation instructions here: Stop cpu from overheating

As an aside I've read a few questions the last two weeks from people wanting to override the minimum frequency, maximum frequency or to fix the current frequency at a specific speed. As such I've decided to create a new bash+yad GUI project. A tab to display temperatures for all thermal zones and issuing notify-send (pop-up bubble messages) will be part of it. As well some sort of session log file for when you weren't watching the screen might be kept.

I just had the idea 2 hours ago whilst rereading this thread. No promises on doing the project but I think a few people would like it and I would have a lot of fun :)