If you're looking at the front of the miner where the ethernet pug is your board series is 1 to 3, right to left. So if the far right cable is plugged into the far right board it will display as chain 1, middle to middle is 2, left to left is 3. Again, If you swap the cables and cross them this will change only how the chains are displayed in your UI page.
Great, just what I was looking for, Thanks!