How to Determine the Proper Size of a Power Supply for a PC

When building a new PC or replacing components on your old PC, it is always important to ensure that you have sufficient power to accomplish the task at hand. This means selecting a power supply that is capable of delivering the amount of wattage you need to fuel all of the parts and pieces of your computer. Fortunately, this is a fairly simple task that can be accomplished easily.

Things You'll Need

• Video card instruction manual or specifications

Instructions

1. Consult the operating instructions for your video card, either by looking at the hard copy that came with your card or by looking at product specs online at the manufacturer's site.

2. Look through the specifications until you see a line stating "Recommended Power Supply." This is the level of wattage that the maker suggests for an average computer using this card. Note that this number is not just the amount of power it takes to run the card, but it is the amount of presumed power that will be required to run an entire computer with the card attached.

3. Add 50 to 100 watts to the recommended total to be safe, then purchase a power supply that has that level of power. For example, if your video card recommends 400w of power, purchase a power supply that has 450 to 500w to overshoot the mark slightly. Remember that having a larger-than-needed power supply will not harm the computer, but falling below the power requirements of your machine will.

References

• Five and Dime: Power Supply Requirements