And it should throttle if needed to stay stable.
I think that this problem was related to coral somehow, it’s getting quite hot on heavy workloads, especially with max package, as far as I remember it will throttle at about 115’C. According to specs it needs cooling from both sides to move heat from IC as well as its NPU.
Basically there are two libs for it, std and max, second one will use higher frequencies and throttle at higher temp. Also If You have dual edge tpu You don;t have that small heatsink.
If You used that in passive case then it’s clear why it added heat. Especially on high workloads when all resources are used. If You also added nvme on bottom then it’s another source of high temp, this depends on particular m.2 board.
I learned something about RAM on one of my (8gen) NUC, it was stable with 32GB RAM, but adding another 32GB caused instability. Then I needed to get it out of rack and tested on table, it was ok. So I needed to find what is wrong, quick memtest was always ok, but when I left that for night it showed some errors. faulty RAM? I switched them and same result. Then I placed big fan on top of that, night test passed. So it was stable when it was cold but on workloads after some time lower RAM module has switched several bits. Proper cooling solved issue and same unit work about 6 months with no issues.
If board is warm retest everything with big fan blowing directly at everything. If this solves issues then maybe on long workloads there is something related to temperature. This is especially true for passive cases where many are designed for mostly idle usage. Of course software, kernel is something to keep in mind too. Good luck