Looks like a power overload to me. You sure you have them hooked up right to the S9i? e.g. only one power supply per hash board?
That has a grounding setup that allows both psus to be as one.
Ie you should be able to use any cable on any board.
My guess is a defect in the pcie cables.
Every once in a while parallel miner sends out a bad cable with crossed wires.
At op look at every pcie cable to see if they done correctly. I have a thread with clear photos of this issue
I will go to a real pc and find the thread for you.
Found the thread check it I bumped it just for you.