Your Power Supply: Is Bigger Really Better?

If you're a casual auto enthusiast, such as myself, you may have noticed that the German Automakers seem to be in a bit of a tiff. BMW, Mercedes, and Audi have been ramping up the size and power of engines in their cars drastically. This horsepower war is incredible if you regularly drive on the Autobahn and make a quarter of a million dollars each year, but for more practical driving, the massive engines in these fine German sports cars are as much a burden as a boon. They're loud, they're expensive to repair, and they use tons of fuel. In other words, there is not much point in buying one unless you really do intend to drive outrageously fast.

I know, I know. I just used a car analogy, one of the most abused forms of explanation in the PC industry. But the same sort of war seems to be raging in the power supply market. Today, nearly every enthusiast power supply maker has at least one desktop model with a rating of over 1000 watts, and some power supply companies offer multiple power supplies with ratings over that mark.

But how much power do you really need? Many computer enthusiasts have come to think that a power supply of at least 500 watts should be considered for most systems. In truth, the amount of power needed by most computers is far less than that - and buying a smaller power supply can save you a ton of money.

Part of the reason that the power supply wars have continued is due to specifications from hardware manufactures which, while well suited for keeping the company out of legal trouble, don't reflect reality. For example, the product specifications page for the Radeon 4xxx series of cards recommends that the Radeon 4870 run on a computer with a power supply of at least 500 watts.

So what happens when you use less than that? As I can tell you from experience, nothing bad at all. I run a Radeon 4870 on a 430 watt Antec power supply without a single problem. But I have more than just my personal experience to provide as evidence. More telling are the power draw benchmarks that can be found attached to most reviews of high-end video cards. While ATI recommends a 500 watt power supply be used with the Radeon 4870, a system using a Radeon 4870 actually uses around 250 to 300 watts under full load. Note, this is total system power draw, not just the power draw of the video card. That's right - you can run one of the most powerful video cards ever made on a 350W power supply.

In fact, the 500 watt mark which is used as the offical recommend minimum by ATI could operate a system using two Radeon 4870s in Crossfire under full load. That, of course, would be cutting it a bit close for comfort, and you may run into problems if you happen to also be using a power-hungry CPU like a Phenom 9950. But the fact that it is possible to run so much hardware with what is popularly considered a meager power supply illustrates how large the gap has become between what is perceived as necessary and what is actually necessary.