How do I determine how big my power supply is?

Computer power supplyYou can determine the total output of a power supply by physically examining it. All power supplies, like the one shown to the right, have a sticker that gives all important specifications, like total output. For example, this power supply would list the total output as 330W (330 Watt power supply).

If you have a computer that is already assembled, you can determine how big the power supply is by opening the computer case and examining the unit.

PSU side sticker

As can be seen in the above image of its sticker, this power supply is rated at 500 Watts (500W). Many power supply manufacturers also use the wattage of the power supply in the model number. For example, this power supply's model number is APS-500S, which is also an indication of a 500W PSU.

If you're unable to locate a sticker on your power supply, it's possible that the identification may be on the side that is not visible. If this is the case, you need to remove the power supply before being able to identify it. The steps in doing so are listed in the Additional Information links listed below.

Additional information