But for electronics basically all heat is excess. Brakes are literally supposed to turn kinetic energy into heat. A GPU is supposed to solve linear equations quickly. The generated heat is because we don't know how to not generate it. If I could power my oven with all the energy waste while playing Crysis I totally would.
Plus, heat of the brakes is also technically waste. Case in point, Formula 1 cars have specially designed systems whose purpose is converting energy dissipated during braking back into battery charge to power the hybrid engine.