I have assembled my desktop PC about 2 years ago. It’s fairly beefy (AMD Ryzen 9 3950X 16-Core Processor, 128Go RAM, nVidia RTX 3080 Ti). It’s running debian stable.

Once in a while (not that often, but like every 2 weeks or so), seemingly at random times, not especially under heavy loads, the system crash and freeze, irresponsive to even the linux sysrq magic keys. I never manage to find what was the cause. One interesting fact is that when it happens, for some reason it seems to “freeze my network” too, ie, other (ethernet) devices on my local network have no connectivity anymore. They’re all connected to the same router, but not through this crashing PC. Connectivity comes back as soon as I force shutdown the crashing PC.

What can cause this and how could I fix these freezes?