Do It Yourself Computer Part Six: Power Supply

Today’s processors can draw as much as 125 watts of power, more than the brightest light bulbs in our homes (thankfully they do not glow like them!) Adding multiple video cards and hard drives to a system can quickly bring a cheap power supply to its knees, so it is important to give special consideration to choosing a dependable power supply for your computer.

There is a sweet spot for most modern systems when it comes to power which can usually be found in the 400 to 500 watt range. Unless you’re planning to run multiple high-end graphics cards, dual processors, or a large volume of drives such as a RAID array, you probably will not need more than this, but every system is different, and you should find yourself a dependable guide to help you calculate your power needs. Try Googling “power supply calculator” for more help there.

Many people tend to make the mistake of going with a cheap power supply in their computer system, as the power supply does not directly add to increased system speed, but if you do the research, you will learn how important a dependable power supply can be. Cheap power supplies can provide uneven or irregular voltages, which can damage the sensitive parts like the motherboard, processor, and drives.

Cheaper power supplies also often do not truly meet their power claims. Just because a power supply says that it can achieve 550 watts of power does not mean that it will do so consistently and unwaveringly. Most builders will advise to you select a power supply 30-50% higher than your initial needs, so that your power supply is not struggling to provide its full capacity all the time. This practice will also allow you to upgrade your system later without having the additional cost of replacing the power supply.

A common power supply. Image via Wikipedia

Other important considerations

If you’re going to be running SLI or Crossfire (multiple graphics adapters) either from the beginning or down the road, make sure your power supply states that compliance. Most modern mid-range power supplies can support both, but if your motherboard supports it, you’ll probably want to leave that option open to you down the road. Buying a single video card today will probably suit your needs, but next year you might like the performance bump that adding a second card could offer – and the compatible cards will likely be significantly cheaper later on.

You should also make sure that the power supply has enough connectors, and the right types for your needs. Count the number of drives, as well as any video cards that will require their own power connections (most high-end cards require at least one.)