Setting your ballast to overdrive can produce frequencies that are damaging to your lamp. Damaging frequencies distort the arc stream in a lamp’s arc tube. These pictures show what happens inside the lamp’s arc tube when your ballast is in overdrive mode. This distortion causes cracking and may rupture the arc tube and destroy your lamp. Play it safe and only run your lamp at its rated wattage.

An example of a Metal Halide lamp in overdrive.
An example of an HPS lamp in overdrive.