I have a little fanless mini PC that runs various stuff around my house, including homeassistant. The case is basically a big heat sink.

It started crashing during backups.

The solution was to stick a fan on it. :( This is literally a box _designed to not need a fan_. And yet. It now has a fan and has been stable for months. And it's not even in a closet - it's wall-mounted with lots of available air around it.