Unexpectedly and suddenly,  my not-so-old daily driver PC has just given up.
It boots but either freezes or reboots after between one and three minutes of activity.
This happens under Windows and Linux, whether booting from the internal (M.2) disk or USB drive.

I have:
  • wiped the OS from the internal disk and tried to reinstall
  • updated the BIOS to the latest version (Gigabyte motherboard, Ryzen CPU)
  • Booted safe mode under both Windows and Linux (tuxedoOS)
  • removed all peripherals (using the mobo onboard video)
  • checked that the CPU temperature is under 40C idle, at one point  opening the case and pointing a floor fan at it.
  • swapped mouse and keyboard
  • run memtest, zero errors
None of this has helped.

Any suggestions? The culprits appear to be down to CPU, motherboard and power supply. I would really prefer not to have to replace all three.
Sent from my laptop... any help, or suggestions of where to take this thing, are appreciated.

--
Evan Leibovitch, Toronto Canada
@evanleibovitch / @el56