KIND OF related to this topic (Antminers breaking and then hacking them...):

I didn't realize until now that different versions of the S9 and their hashing boards MAY not be interchangeable due to the fixed frequency vs. auto tune versions, as well as other minor changes.

I searched all over the net to try to figure out the version history of the S9, and what's compatible and what isn't but I came up empty.

Does anyone know how the different versions of the S9 control boards and the hashing boards match up? E.g. my S9s are version 1.6. and I just bought a version 3.75 hashing board to replace a failed one, but realizing my ignorance I thought I would find out if they are compatible before I drop in the new hashing board.

I think this info (like a compatibility chart) would be very useful for anyone who needs to replace a hashing board or a control board. They come up for sale on eBay every once in a while but it's better to be sure in advance if what you are buying will actually work...

Any words of wisdom on this would be greatly appreciated.