Saturday, July 16, 2005

Sixty-five or Eighty Percent Efficient?

Pardon my long silence, which I attribute to two things. One is that the President hasn't said a whole lot about Social Security lately, the other is that I've been busy working.

Which brings me to an observation about efficiency. Laptop computers run very nicely with a power supply that provides less than 100 watts - including the built-in video display. Desktops typically require 300 or more watts, plus whatever your video display draws. PC's are one of the bigger electric power consumers in the USA. So, it is nice to know, if electric power ever either gets scarce enough or expensive enough for people to notice, there is a whole lot of room for improvement.

Another little noticed efficiency item for computers is how efficient the power supply is. Most typical desktop computers, to get that 300 or so watts of power on the inside of the computer, use a power supply that is 69% or less efficient. That means they require something like 550 watts from your AC power line to deliver 350 watts to your CPU and assorted accoutrements.

But there are also power supplies that are 80% efficient at converting power from your power line for use by your power-hungry peripherals. If you've got one of those, instead of 550 watts, you only need 440 watts to power your dream machine.

The difference, if you like to leave your PC turned on all the time, is something like 1000 kilowatt hours every year, or for those who pay ten cents for a kilowatt hour, about $100 - every year.

If this total lack of awareness of something that costs 50 or so million Americans $100 a year of wasted electric power bugs you, here's something you can do about it. Next time you buy a PC, shock the hell out of the salesman, and ask them what the power bill to run the thing for a year would be. If they can't tell you, ask them if they know the efficiency rating for the power supply for the PC. If they can't tell you, tell 'em "have a nice day" and walk out.

You could also ask the folks that put those Energy Star stickers on things like washing machines and refridgerators don't put the same stickers on PC's, showing how much it costs to run one of the things every year. It'd be a real eye opener for a lot of people, to find out their $250 PC might cost them another $250 a year to run.


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