[GeForce GTX 480 Over-Voltage]
In Afterburner 1.6.0 Beta 4, you can adjust the voltage of GeForce GTX 480 from 0.825~1.125V. It's not very big adjustment range, but considering egg-cooking capability of GeForce GTX 480, it is safe to stay in this range.
GeForce GTX 470 over-voltage support will be ready in next version.