On KDE there’s System Monitor, which you can customize to show graphs for CPU usage and temp, among other things, and GPU usage and temp too.

For in-game monitoring there’s Mangohud, also very customizable on what you can show in the overlay

Mission Center, UI kinda like Windows 11: https://flathub.org/apps/io.missioncenter.MissionCenter

htop and nvtop on split terminal window ?

I use “GtkStressTesting” for tracking system’s health, although it’s actually a Benchmarking tool.

https://gitlab.com/leinardi/gst

Resources is a nice aio flatpak for system monitoring.

bpytop is very nice and functional. Maximize the window and it almost hypnotic to watch.

https://nicolargo.github.io/glances/

If you’re using an amd gpu, corectrl gives you a ton of info and controls.

Msi afterburner on windows

Resources is pretty good.

Btop++