I am running Ubuntu 24.10 on a Dell Inspiron 5502 laptop. I am not sure if this is an Ubuntu issue or a Dell issue. I noticed today that the thermal management changes I make in the BIOS are not staying saved. I select quiet mode from the power management options, but when I go back into BIOS following boot, I see they have gone back to 'optimized'.
If I make the changes in BIOS, switch the computer off and then back on and go straight back into BIOS, then the changes stay set. They only change after a boot up. However, other changes (such as turning off c-states remain set as I set them). I am not sure if this anything to do with Ubuntu or if it is a separate Dell issue. I didn't use to have this problem. It seems to have happened after updating the BIOS, but may have started after upgrading to 24.10. I don't really mind. I just want the fan to be as quiet as possible because I use the laptop for recording vocals.
In the end I realised that it was the power-profiles-daemon that was causing the issue. I removed it with:
sudo systemctl disable power-profiles-daemon sudo systemctl stop power-profiles-daemon
...and was then able to choose the 'Quiet' mode from the Thermal Management section of the UEFI on my Dell Inspiron 5502 without the daemon changing it back to 'optimised' on boot (it stays in quiet mode). I don't particularly care about getting the most out of my battery because my laptop is plugged in most of the time. I just cared about keeping the fan quiet. I am now a Happy Camper until the next inevitable tech headache...