Power efficiency is calculated based on the ratio between AC input and DC output of the power supply. With improved power transfer, the efficiency level is increased. This can be achieved with a good circuitry design and quality components.
Improving Quality of Power Transfer
With PFC (Power Factor Correction), a power supply is able to reduce the current and stress levels on the various components in the power unit.
Heat Reduction of the Power Supply
A cool-running power supply means less risk of overheating your computer system. The end result is prolonging the usage of the computing system.
If the power supply takes longer to heat up, it means the intelligent fan is turned on less often, thereby minimizing computer noise.