Computer Power Supply Units or PSUs convert mains Alternating Current (AC) to the Direct Current (DC) required by computer parts. Power supplies are typically rated in watts of power they can reliably supply to a computer. But these PSUs aren’t 100% efficient at their job. Some power is lost during the conversion from AC to DC. How efficient they are at their job determines how much electricity your computer uses and that is reflected in your monthly electricity bill.
May 22nd, 2011