How To Buy a Power Supply Unit

Posted on Nov 5 2009 - 11:36pm by Christopher Allega

An efficient power supply unit (PSU) is the heart of your computer system. You will have fewer problems adding new components to your rig and fewer quirks in getting them to run properly if you start with the right power supply. More importantly, you’ll reduce the risk of a catastrophic failure that could take your system and your data with it. But unlike CPUs, motherboards, or graphics cards, PSUs’ specs don’t always immediately offer up all the most important information you’ll need to pick the one that’s right for you and for your system.

Buying the right PSU involves a combination of math and a healthy dose of Web searching. You probably know you need to determine the total power requirements of the system you are building—or that you may want to build someday—so you can get the right PSU to meet your needs. But you’ll also need to decide what kind of connectors you’ll want for your components and whether they should be modular, how many 12V rails you want it to have, and whether or not it’s worth buying one that is friendly to the environment.

Your first task is to calculate how much power you’ll need your PSU to supply. Antec has a thorough power supply calculator that takes into account almost every potential system component, including specific choices suited to overclockers and those whose systems contain multiple graphics cards. When entering your components, make sure you take into account everything you intend to add to the system, including system cooling fans, liquid cooling elements, and even peripherals that may draw power from the USB or FireWire ports to which they’re connected.

You also need to consider how clean the power is that the PSU is putting out. Ripple is defined as to how badly the PSU’s voltage fluctuates over time, especially when higher loads are placed on the unit. Excessive ripple can cause problems for some system components, even to the point that they refuse to operate.