Hardware.Info posted How powerful does your PSU really need to be?
A quote from the article:
Every PC-building hardware enthusiast has asked themselves at some point: what capacity should power supply have for this build? Many people are tempted to buy a power supply that's more powerful than necessary, just to be sure that it'll be powerful enough, and waste valuable money in doing so. But there's no need to panic - our extensive power supply tests will help you make the right choice for your computer.How powerful does your PSU really need to be? @ Hardware.Info