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How Do I Choose a Power Supply for My PC

October 03, 2011  |  Difficulty: Hard

How to choose a good power supply unit for your computer

If you are choosing a good power supply for our computer, you need to take many factors into account that will affect your choice. You may have read information about the minimum power supply needed, as written on the package box or in instructions. However, this information is not usually relevant because the manufacturer does not know what other components you are going to use. It is obvious that power supply requirements are different for each workstation, but generally the guidelines below can help you choose a good power supply unit for your computer.


  1. Standard – First you must know which standard power supply unit is needed. Nowadays, you will mainly see AT and ATX types. The standard for your needs depends on your PC case and motherboard, but ATX is the standard used for most modern computers.
  2. Output Watts – This is generally the most important parameter. You need to calculate the power requirements of all your components. A manufacturer often will provide this information, or you can use an online calculator. Be very careful with this, it is recommended that you buy a bit more powerful supply than the value you calculate.
  3. Brand – The power supply unit delivers energy to all your computer parts so don’t skimp on quality. If possible avoid cheap units. Try having a look on forums, or ask a seller about brands and at the very least buy a mainstream brand. 
  4. Cables – Consider the size of your case and the arrangement of the components in it. Be sure to buy a power supply unit with cables that are long enough.
  5. Connectors - Check the connectors you need for plugging in all of your components. If you like, make a list of connectors you need and check the product specifics.
  6. Fan – For a power supply unit use the same rule for any other computer fan, the bigger, the quieter. Logically, this rule runs parallel with the quality of the fan, so it’s best to buy a good-quality power supply with as big a fan as possible.
  7. Ac Input – Be sure to buy a power supply unit with an AC input that you can provide.

Tips and tricks:

  • If you can’t decide which model to buy try holding them in your hands if possible. Generally, the heavier power supply is the better choice.
  • If you are missing some connectors, you can usually buy replacements for them.
  • When you are counting the wattage for your component, be sure that you multiply the result by 1.2 times so you’ll have a 20% reserve for the future (i.e., if the total supply needed by the parts is 325W then multiply 325 by 1.2 which equals 390, so you should buy a 400W power supply unit).


  • Do not forget to count multiple devices in your computer separately. For example, if you’re going to install two graphic cards, and each has a 50W power supply requirement you need to count that as 100W. The same goes for hard drives, optical drives, etc.
  • Remember that each and every part in your computer needs power.

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