Computer Power Supply Wattage

The power supply is there to convert the high voltage from the wall outlet into the lower voltages required to operate the computer circuitry. If this is not done properly, the irregular power signals that are sent to the components can cause damage and system instability.

Because of this, it is important to make sure you buy a power supply that meets the needs of your computer system.

The peak output rating is the highest amount of power the unit can supply but this is only for a very brief time. Units cannot continuously supply power at this level and if it attempts to do so will cause damage. You want to find the maximum continuous wattage rating of the power supply. This is the highest amount that the unit can supply stably to the components. Even with this, you want to make sure the maximum wattage rating is higher than you intend to use.

There are three primary voltage rails inside of the power supply: +3.3V, +5V and +12V. Each of these supplies power to the various components of the computer system.

It is the combined total power output of all these lines that make up the total power output of the power supply. The formula used to do this is:

  • Wattage = Voltage * Amperage
 
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