A Green Power Supply?Sea Sonic SS-650HT

Even the most hardcore DIY PC enthusiast may still be surprised to learn that the power supplies in most computers (PSUs for short) aren't designed for energy efficiency. In fact, most computers drain more power than they need during normal operation, leading to higher electrical bills and a more dire environmental impact.

The 80 Plus program (www.80plus.org) is a voluntary certification system for power-supply manufacturers. The term "80 Plus" is a little complicated, so bear with me for a moment. If a PSU meets the certification, it will use only the power it needs at a given load: In other words, it won't use more power than it needs. For example, if your PC requires only 20 percent of the total power of a 500-watt PSU, the system will consume no more than 100 watts. Only when the PC requires full power will the PSU run at the full wattage load.

It's a little like that highly efficient furnace in your home: Instead of just operating at full capacity, an efficient furnace will throttle itself to heat your house using as little power as possible, with no overheating. Older furnaces just push out constant heat to keep you warm in December.

An 80 Plus power supply can save about 85 kilowatt-hours per PC, per year. In many ways, it's the heart of a green PC, since it manages the power for all the other components. It also has the most dramatic effect on your energy bill. Of course, all 80 Plus power supplies are also lead-free and RoHS-compliant.

I chose the Sea Sonic S12 Energy Plus 650 power supply (www.seasonic.com), an 80 Plus-certified product that runs quietly. In addition, it complies with the ATX 12V and EPS 12V specifications, which also address the issue of power draw. The 650 uses only the power it needs, unlike older PSUs that manage power less efficiently; an inefficient 500-watt PSU typically drains more than 500 watts of power. Worth noting is that the 650 has all the connections I need for SATA and IDE drives and uses a large underside fan for extra CPU cooling. There are some power supplies out there that draw less power but the 650 gives you the option to grow in the future. It's a heavy bugger; at 6 pounds, it weighs almost as much as a computer case, but I can live with that if it means the Earth is happier!