I wouldn't call that a spike or a surge, more of a variableness, which is quite common in PSU's. You're hard pressed to find a PSU that stays constant at a exact voltage level (if it's even possible) w/o a little fluctuation. The time to worry is when a RAIL goes from, say, 12.014 to 14.00 or 9.00, than it's time to rip the hair out.
Is that a standard 6800? Meaning non-GT/GS/etc.? I cannot comment personally on that mobo, but if I was you, I would leave the oc'ing alone, personal experience hasn't warranted enough performance boost to make me care about oc'ing, but maybe you'll find different.