Core voltage is for high CPU frequencies (Core Speed)
You only want to increase you FSB voltage if your fsb gets pretty high, I have the 680i, and have gone from 1333 fsb to 1893, and have not had to increase the fsb voltage, just vcore. So i would say dont mess with fsb voltage
I would just add vcore and if it becomes unstable and your running a high FSB then I would proceed to add FSB voltage. I would doubt that you would need it anyways for your quad.
i had a bad chip got a new chip in, and now im on a stock hsf becuase my watercooling isnt all in yet. But, ill know within the week, and ill post my results.