Some would argue that the power supply is the most important component in your build, and if you've ever had a cheap, generic PSU blow up on you, then it's easy to see why. But learning to steer clear of no-name brands is only part of the equation, the other consideration is what size unit do you need?
That's where OuterVision's "eXtreme Power Supply Calculator" comes in, a handy online utility designed to give you an idea what size PSU you should be looking at. The way it works is you select your system configuration from a series of pull-down menus and checkboxes. There are over 1,100 CPUs included, and you can even calculate how much extra juice you're pulling by overclocking to a specific frequency.
It's been a couple of months since the last update, and the June refresh adds some new components to the list. The PSU calculator now recognizes Nvidia GeForce GTX 465 videocards, and a handful of AMD processors have been added, including the AMD Phenom II X6 1055T at 1.3V and 1.1V, and the 1090T clocked at 3200MHz.
If you plan to use the utility, be advised that the 'System Type' pull-down menu is asking for how many physical CPUs you have your in systems, not the amount of cores. A quad-core chip, for example, would still count as "1 physical CPU."
How much wattage are you pulling, and what's your PSU's make/model?