Actually, I think cpupower-gui showed a lot! Thanks for the suggestion.

After a boot, cpupower-gui shows each core is stuck at 800Mhz, after a sleep/wake it behaves as expected and boosts up to 4Ghz when needed.

Today after a system update and a clean boot, the problem was not replicable any longer. Maybe a patch fixed it?

Nothing was specifically patched. Generally speaking the only relevant update might be the kernel update but if you update daily it was not in today updates.

I find it more likely that by running cpupower-gui you fixed its behaviour at startup, because in the old report there was this in the logs:

cpupower-gui[5372]: Applying configuration...
systemd[5330]: cpupower-gui-user.service: Main process exited, code=exited, status=255/EXCEPTION
systemd[5330]: cpupower-gui-user.service: Failed with result 'exit-code'.
systemd[5330]: Failed to start cpupower-gui-user.service.

These considerations are based on and limited by the information I have.

I'll try to be as precise as possible regarding what I did then. When you suggested to check the CPU frequency with cpupower-gui I did the following:

1) fresh boot of openmamba. run cpupower-gui and noticed CPU being stuck at 800Mhz on all threads.

2) sleep/wake the system. cpupower-gui shows CPU clock boosting correctly. Now I did update and a kernel update was included in the update. This doesn't do good to isolating causes, I agree.

3) rebooted. run cpupower-gui and noticed CPU boosting correctly.

I was not aware that there is a cpupower-gui-user service. I do not know cpupower at all, I thought it was just a utility to show CPU behavior, I do not know if it actually does act on the CPU behavior.

All I can say besides that is that this issue appeared in every installation of openmamba I have done on this system. I hope it's gone for good on this installation!

This issue returned, after reinstalling openmbamba and removing .config

I have not installed and run cpupower-gui yet, maybe we can investigate and find the root cause?