I can only speak in regards to the 3 I have and pretty much yes, slow creep down from 220
You did not understand me. I read the information on the Internet. The problem of hash rate in AMD is not due to the deterioration of equipment, but to the increase in the generation of DAG. Therefore, a decrease in the hash rate should be uniform across all similar devices. And I have a hash rate 178 on one liner, on another 162. It's very strange and it seems to me that it's possible.
If you haven't installed the DAG fix drivers from AMD your Panda will slowly drop over time on ETH.
The B3 should run stable 229MH/s on 220V with the latest software installed.