Power supply efficiency is the amount of power that a power supply unit (PSU) can convert from the AC power from the outlet into DC power, which is used by your computer components.
PSUs are never 100% efficient, meaning not all the power they draw from the outlet is converted into usable power. Some of it gets lost, mainly in the form of heat. The efficiency of a PSU is the percentage of the AC input power that’s converted to DC output power.
For example, if a PSU is 80% efficient and your computer uses 400 watts, that means the PSU actually pulls around 500 watts from the wall. The other 100 watts are dissipated as heat.
A higher efficiency PSU will waste less energy as heat and will therefore require less cooling, leading toquieter operation. Moreover, it will also result in slightly lower electricity costs over the long run.
What is Power Supply Efficiency
Power supply efficiency is the ratio of output power generated by a PSU to the input power it consumes to generate the required output power. Mathematically,
Efficiency= output power/input power
Expressed in percentage, power supply efficiency gives you a tentative idea of how much AC power the PSU actually converts into DC. This way, you may know the useful power and the power that goes to waste, often in the form of heat.
The lower the power supply efficiency of your PSU, the more electricity it wastes and the more heat it generates
For instance, you have a PSU with a wattage rating of 1000W and 50% efficiency at a full load. Based on the above formula, here’s the calculation of how much power it will draw from the wall socket to provide the output of 1000W:
This means that the PSU draws 2000W and supplies 1000W. The remaining 1000W does not make it to the PC components.
However, there are almost no PSUs that are this inefficient. Most of the PSUs these days provide efficiency anywhere between 70% to 80%. But there are also PSUs that provide an efficiency of 90% or higher.
This is where the 80 PLUS certification comes in and standardizes the efficiency rating.
Power Supply Efficiency Rating
PSU manufacturers generally rate their power supply units with the “80 PLUS voluntary certificate program.” Introduced back in 2004, the 80 PLUS rating certifies that the PSU can maintain a minimum of 80% efficiency at varying loads.
