Yes, that can be true: probably it was really 625.

I had several other problems with that model, such as sudden reboots (not temperature related) and sudden stop of hashing.

This was then probably related with the frequency of 625; i do not understand why this is then the frequency factory set from Antminer.

In the end: miner is stable now and on low temps, even with slighty lower hashrate.

What would one want more ?