I'd just bump it by multiplier, start at 3.2ghz and stock volts, see how stable it is, if it's good, go to 3300, etc, until it won't work, then toss the volts up a notch (1.38 to say 1.41) and continue. i'd expect a 3.9ghz oc total, like 1.5 v probably.
make sure to keep your ram loose, don't...