the wattage of a power supply is potential output.in other words if you have a component drawing 50w @12v the power supply will deliver 50w @12v.if the component draws 100w the power supply will deliver 100w. its the same with power supplies of any kind including phone chargers.the psu will deliver the wattage required by the component up to the max rating on the power supply.so,no,damage to components will not happen.neither is it bad for the psu.