The Rampage IV Extreme automatically applies some overclocking to the CPUs that are installed on it. It will automatically turn the 3/3/4/5/6/6 turbo bins into 6/6/6/6/6/6. This can easily be bumped to 7/7/7/7/7/7 or higher simply by increasing the turbo multiplier.
It is not recommended to overclock the 6 core processors to the same degree as you would normally overclock the 4 core processors as they put out nearly twice as much heat. A 6 core processor draws more than 200 watts of power at 4Ghz.