Introduction

Don’t forget the power

So, you’ve finally decided which CPU, motherboard, and graphics card you want to put into your new computer. But what are you going to do about the power supply? The power supply has always been the most esoteric part of system building. We all have a vague idea that a power supply with more watts is better than one with fewer watts. We also know, and expect different manufacturers to have different interpretations of “peak output.” In other words, you already know that all 300W power supplies aren’t created equal -- you also know that 550W power supplies are overkill for a standard desktop machine.

But how much power do you really need, exactly? Most of you probably don’t know the answer to this. In fact, before last month, I didn’t know the correct answer either. Early on, I used to rely on AMD’s power supply list, but AMD stopped updating that. Since then, I’ve just dropped back to my old-school criteria: start with a case/power supply combo that’s in the range of $50, and then put down extra cash for a better design and cooling.

Why Power Supplies are Important

Everyone keeps talking about watts, and it’s an understandable approach. People always talk about high-end power supplies being one reason why servers and workstations are more reliable than standard desktop machines. For example, SGI Octane workstations have 800W power supplies, even though the highly efficient MIPS architecture CPUs consume only about 17W each, the same as an x86 notebook chip.

But this is the wrong way to pick out your power supply. You first need to decide what the rest of your system will look like, and figure out how much power that takes. Then you can buy a power supply that meets your budget. Sounds simple, but there’s one little secret…