You were caught driving at 124mph what conviction will you get?

Depends on the circumstances and where you were (public road/race track/time trials/Bonneville Salt Flats). For a public roadway I can immediatley think of several, which may or may not be applicable in your jurisdiction (careless driving - reckless drivng - reckless endangerment - driving too fast for conditions - criminal negligence - failure to maintain proper control - etc).