@screenbeard@aus.social A while back I had Linux on a old MBP and was disappointed with the fans being noisier than under OS X.
Try installing TLP linrunner.de/tlp/index.html. It's mainly for laptops but will reduce power usage on any system.
Powertop can help you see what is keeping your CPUs awake.
Consider removing baloo (KDE) or whatever the gnome equivalent is. Those file indexers tend to run indiscriminately.