This is log with thierry4wd's firmware, also had the same issue: https://pastebin.com/KY7VkBrN

https://imgur.com/a/aQlWI8r

I have switched, bad board to middle position (board 6), also mixed power cables just to be sure that the problem isn't in PSU, also switched to Braiins-os.

and still have the same problem. Now middle board keeps dropping to 0.
here is the log:
https://pastebin.com/TRcTBPea

I would like to try thierry4wd's firmware but for patch link is expired.

Yes I agree it must be board 3.
It kind set itself. From last night (21:00 approx.) I had 0 restarts, CRC error counter remained the same and no hash rate oscillations on all boards.

I believe that auto frequency found best setting for that board which is 8.9 Volt and 656 Mhz.

Since the seller agreed to send me a new board for free. Is it safe to run miner with all 3 boards or is better to disconnect  faulty one?

Hello. can somebody help me, I'm having S9 with latest stock firmware, but one of the hashboard works shows normal GH/S(RT) and after few minutes 0. and thats keep going all day. i have tried different firmwares, unplugged and replugged all the cables a but the result remained same.

Here is log(its divided into 3 links due to the size) and pictures.

https://imgur.com/a/bbLqFf8
https://pastebin.com/ZLAJynQk
https://pastebin.com/BLVznWvr
https://pastebin.com/u6aJw7Hr