Hi guys
Which hashboard is hashboard 1 (chain 0)?
Closes to the PSU for example.
Maybe @mikeywith can help me?

Physical place does not matter. Check data connection cables.
IIRC order is:
0 3
1 2
They are marked on control board, you will have no trouble finding this out by yourself. If you have troubles, then send a picture of control board, and I will circle it for you.