Unplug all boards and test them one by one. if they all work individually, try two at a time in all the combinations. We can go from there, but there is no point in trying to diagnose it before testing all the boards.

Take a look here for my reasoning, very similar issue: https://bitcointalk.org/index.php?topic=2599853.0

Ended up I had a board that was a couple versions older and it was causing any boards plugged in with it to not hash as well.