Have you actually been able to set your multiplier to 60, so that you're getting a 6.0GHz overclock? That would be amazing. If you're just saying that your motherboard's OC software lets you try to set it that high, not so amazing.
Start with stock voltage settings. Move your multiplier up by 1 or 2 at a time until you reach a point that is not stable or won't boot. Then try increasing the Vcore (CPU voltage) a little bit at a time, not going much higher than 1.4 volts. Continue to increase multiplier and voltage in small increments until you reach your "wall" - the point at which you can't create a stable overclock.
Don't set your voltage too high! Try to stay below 1.4V for a "practical" OC.