The color green

For years and years, computing was all about performance. Faster CPUs, better video cards, more RAM—all to make sure you had the biggest and baddest box on the block. Recently, we've seen a new trend, focused mainly on lower-energy, more efficient computing. The marketing buzz says that a green PC will result in reduced power bills, smaller servers, and lower carbon footprint for the environment. Couple this lean approach with reductions on hazardous substances (a la RoHS) that have been made over the past two years, and computing is clearly becoming less wasteful.

For corporations, a 10 percent or even 5 percent reduction in power consumption is huge. Add in additional overhead costs to keep those server rooms air conditioned, fed with clean power, secure from the outside and the inside, and the effects of a greener computer are multiplied. Smaller, more energy efficient servers may allow more servers to be packed into less rack space—this may actually increase overall power consumption, but it might also allow one less data center to be built, which means one less building to staff and all of the other associated costs.

For the home user, the benefits are more direct: a lower electric bill, both from reduced consumption and, for those in hot climates, less money spent on cooling your home office. The primary trade-off for individuals is the direct cost of upgrading or replacing an existing system to a less power-hungry one: you may never recoup the upgrade cost, even if the computer is run continuously. At $0.14/kWh, going from a computer that consumes 100W to one that consumes 60W would save $50 a year—which is many times less than what it would cost to upgrade the computer.

If your existing system is a power-hungry Netburst-era Pentium 4, the savings may be more dramatic than the example above, but even if you save $100 a year, upgrading a perfectly adequate computer for the sake of lower power probably doesn't make financial sense. At $300 for a minimal box, that's still three years to pay it off, which is a long time for a computer.

Hence, the real reason to go green is because you want to. Be it bragging rights over the neighbors, maybe your existing system is ready to be retired, or because removing 20 or 30 or 50 or 100 watts of power consumption in your study means you don't have to run the air conditioner, we're happy to see what's available for when you want to go green.

Low-power components

Certain components are major power hogs in a modern computer and can be made more efficient, while others consume relatively little power. It's difficult to achieve practical gains with other components.

Processors and power supplies get most of the attention for good reason, but video cards should not be overlooked. Hard drives are another good place for saving power with more efficient units, especially if you can afford to go to flash-based (solid state disk, also known as SSD) drives.

Once you get past the obvious, shaving watts becomes more difficult—but we're hear to help. You can get by with fewer fans since your system runs cooler, and a smaller case means fewer materials and resources used in manufacture—many of which are recyclable. Integrating everything into the motherboard means fewer add-in cards on PCBs, but again, that may only go so far. Not everyone can turn to integrated video, particularly gamers and multimonitor power users, and "ridiculous" comes to mind when one is obsess over the number of fans in a system, as a low-flow/low-noise fan is typically less than 2 watts.

If you can get by without a desktop, a $499 laptop today typically has power consumption in line with a low-power PC. Even more economical alternatives such as Asus's Eee PC are also worth considering, but such choices call for significant compromises in screen size and performance.

The truly obsessed will find little ways to save power, far beyond what we discuss here. The Intellplug is one of the more practical examples.