How to Detemine What Size Power Supply a Computer Needs

When building a computer system, the power supply unit (or PSU) is one of the most often overlooked components. A poor-quality or underpowered PSU can cause failed boot-ups, unexpected crashes and compatibility issues, just to name a few potential problems. In this article you will learn what makes a good PSU and how much power you will need to keep your computer running stable and happy.

Instructions

Choose Your PSU

1. Invest in quality. Most computers come factory equipped with cheap power supplies that are adequate for most home computing needs. However, if you're replacing a faulty PSU or building a new computer, invest in a quality brand with a good reputation. They may cost more, but they will save you potential headaches down the road. Antec, Corsair, Seasonic, Enermax, Thermaltake and Ultra all make quality PSUs.

2. Determine your computer's energy needs. For a modern computer with no power-hungry extras and peripherals, a quality 350W to 500W PSU is usually adequate. Multiple hard drives and CD/DVD drives, a high-end graphics card or dual processors would bump your minimum requirement up to 500W or higher.

3. Examine the PSUs +12V specification. The +12V rail powers critical components in your system: the drives, processor and graphics card. 30A is a good number to shoot for if you have a modern graphics card installed. If you have multiple graphics cards or other power-hungry components, you may want to consider 36A.

Tips & Warnings

• Total wattage can be deceiving. For example, a cheap 600W PSU may only be able to supply 18A on the +12V rail, while an expensive 400W PSU will supply 30A. Always check the specifications before buying. If you see multiple +12V rails in the technical specs, simply add the numbers. If you are a gamer with the latest graphics card installed, it pays to buy more power than you think you need. The last thing you want is your computer to crash mid-game because your top-of-the-line graphics card decided to consume 200W.