You should already have a kill-a-watt and measured load of your system at the wall.
Estimate ~20% higher load. Make sure current PS can handle that.
Flip the switch. It will bump voltage up 5% from 1.12 to 1.175. "Stock" clock will be 880 instead of 830.
Fire up your miner. I would try one card first, and then all the cards in the rig. Make sure they are solid. Give it a couple days before trying your other rigs. You can adjust voltage, memory, clock with software just like any other card.
Remember power doesn't increase linearly. You may find it more profitable to run at stock. You will generate less revenue but after electrical (and possibly AC) costs you may come out ahead.
This is why it is important to get solid measurement w/ kill-a-watt on ACTUAL (not guestimated) loads. You then can compare various voltage,clock settings to get your NET PROFITS which is the only thing that matters.