Generally speaking, when compared to higher profile devices like the CPU, the graphics card or the hard drive, the computer’s power supply is pretty much viewed as an underling. But as the lifeblood of the computer, it plays a critical role in ensuring that the power needs are met.

What the power supply does is to convert higher voltage AC current into lower voltage DC current, which powers the computer.

Google said in a 2005 white paper that the computer we use probably wastes 30 to 40% of power because it is using an inefficient power supply.

Google also said that this inefficiency is due to the fact that computer power supply design hasn’t fundamentally changed since the introduction of the 1981 IBM PC - the vast majority of today’s desktop and server power supplies still ship with multi-output voltages, which Google says causes this inefficiency.

Google’s pitch
Google designs its own power supplies that are used in its data centre servers. These are a single-output voltage design and have a 90% or better efficiency rating, which cuts down energy losses markedly. Google believes that this energy-saving power supply technology can be applied to home computers as well.

Google went on to say that even though standard computer power supplies still provide multiple output voltages, most of them are not used directly in computers today. Because of this, Google proposes that this multi-output design be replaced by a single-output version.

This would mean that the power supply would instead produce one fixed voltage - Google suggests 12 volts - which the motherboard’s voltage regulator modules (VRMs) would then convert to the devices specific requirements.

As the power supply would only have to produce one single DC voltage, power supply design becomes easier, as less components are needed. Because of this, the power supply can be designed to be far more efficient at no additional cost. Google said that the efficiency of this design should be about 85%. But if an additional $20 or so was spent on better components, that figure rises to well over 90%.

The 80 Plus approach
80 Plus is an electric utilities funded program whose end goal is the same as Googles’ - widespread adoption of efficient computer power supplies.

80 Plus certifies energy efficient power supplies. An 80 Plus compliant power supply has to have an 80% or better efficiency at 20%, 50% and 100% of the rated load (80, 80, 80) and a true power factor of 0.9 or greater.

This year, additional 80 Plus Bronze (82, 85, 82), 80 Plus Silver (85, 88, 85), and 80 Plus Gold (87, 90, 87) ratings were introduced, which indicates higher levels of efficiency when compared to the standard 80 Plus requirement (80, 80, 80).

To date, 80 Plus has certified 673 power supplies, the majority of which (87%) are 80 Plus rated. Twelve percent are 80 Plus Bronze rated, and only nine power supplies meet the 80 Plus Silver specification. It should be noted that all of these power supplies are multi-output designed.

Only one power supply is currently certified to the 80 Plus Gold standard. What makes this Dell server unit different from all the others is its single-output design - à la Google. Since Dell is now onboard, single-output power supply designs may gain market place acceptance.

So what do you do?
According to the 80 Plus calculator, an 80 Plus qualified desktop computer - one that has an 80 Plus certified power supply - could potentially reduce a PC’s energy cost by $7 per year - based on a 85KWh energy saving and a 8.67 cents per KWh commercial rate.

On the server side, the annual saving is $26 - based on a 301KWh energy saving at the same commercial rate.

But for the desktop PC, a bigger energy saving can be made by just enabling the computer’s power management. The US Environmental Protection Agency says that the annual saving is between $25 to $75.

If I was happy with my computer, I wouldn’t change the power supply. But if it was noisy or needed upgrading then an 80 Plus model would fit the bill.

At Newegg, which sells over a hundred different 80 Plus certified power supplies, it’s now possible to buy a 350W desktop model for under $40. Of course, a dedicated server counterpart is going to cost more.

Computer manufacturers and resellers now offer desktop PCs and servers that ship with 80 Plus power supplies. PCs with that power supply should also meet the latest Energy Star rating for computers. So if you’re in the market for an energy efficient PC just look out for that rating. X

Check Out
Google white paper
80 Plus calculator
80 Plus qualified computers
80 Plus certified power supplies
80 Plus at Newegg
Energy Star compliant computers