TLP and cpu-freq do not conflict with each other. Both can be installed.
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Have you been monitoring your temperatures actively - as mentioned above?
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What is your output of
htop
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Have you tested your RAM? (16gigs should be more than plenty)
Are you using a custom Swap file? -
Can you please repeat what your graphics card is - Are you using Wayland?
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Have you run
sudo apt clean && sudo apt autoremove
sudo apt update && sudo apt full-upgrade
and cycled a full shutdown and then boot sequence?
- What third party PPA's have you added or Gnome Extensions?