Output power (output voltage * LED output current) / input power. This argument is particularly important, if inefficient means a large part of the input power is converted to heat that comes out; if it is installed in the tube will produce a very high temperature, combined with our LED light efficiency than the one dissipate the heat, it will produce a higher temperature superposition. and we all electronic components inside the power supply life will be shortened with increasing temperature. so the power efficiency is to determine the life of the most fundamental factor, efficiency is too low, otherwise consumed in too much heat on the power supply. Generally above 80% on it.