Reboot on low system usage

Hello,
strange issue here… my box currently reboots when the system is mostly idling for about 5-15 mins. Whenever there is a moderate usage, e.g. playing video stream or running a game everything is fine and stable. Did also get those reboots when system resumes from suspend. Before reboot screen just turns black and then system is booting up again.
I’m not yet fully convinced this is a hardware issue as system runs fine when under load. I haven’t found any useful information in the logs with hints towards this behaviour.

System Info from cachyos-bugreport.sh: fdbc510
Got a few errors here, but feel like they are unrelated.

What i have already tried:

  • use alternative kernels: issue occurs on linux-cachyos, linux-cachyos-lts and linux-lts → issue reproducible → unrelated
  • downgrade power related packages (cpupower, upower, power-profiles-daemon) to version from before first crash → issue still reproducible → unrelated
  • check nvme unsave shutdown counters → not increasing → disk ok
  • run from cachy install disk via USB medium (cachyos-desktop-linux-240818.iso) → issue only occurs on resume from suspend, but not when fully idling → not sure yet what that means…
    • have XFCE installed, live is KDE
  • write dmesg to nfs via tee while trying to reproduce error → no more output than local logs

If someone has any more ideas to try before writing this off as a hardware issue I would be grateful.
Thanks for reading!

guess this means a shutdown
did you ever check the power settings ?

power settings look fine. have not configured shutdown/ reboot for any interval of idling.
pretty sure it’s not a regular misconfigured action. if i check last reboots it says system is still running or did crash. forgot to include this info in original post:

> last reboot | head -5
reboot   system boot  6.11.0-5-cachyos Wed Sep 25 08:10   still running
reboot   system boot  6.11.0-5-cachyos Wed Sep 25 08:05   still running
reboot   system boot  6.11.0-5-cachyos Wed Sep 25 08:02 - 08:04  (00:02)
reboot   system boot  6.11.0-5-cachyos Sat Sep 21 10:53 - crash (3+21:08)
reboot   system boot  6.11.0-5-cachyos Fri Sep 20 21:13 - crash  (13:39)

Do you use some kind of undervolting?

I’m running with BIOS defaults and did not mess with power related package configs.