Go green: Shut down idle PCs

March 8, 2008 – 3:26 PM

Q. I’ve heard that frequently turning my computer on and off can hurt the performance of internal parts. But I don’t want to leave it on all the time either and waste power. What’s the best course?

A. While it once might have been true that computer hard drives or power-supply systems could be degraded over time by turning the machines on and off, there’s little reason now not to go the green (and money-saving) route: Shut things completely down if you’re not going to be using your PC for many hours.

Recent tests at Canada’s University of Waterloo found that computers with Pentium 4 processors running at 1.7 gigahertz drew 110 watts of electricity while booting up and 60 watts when they were on but idle. A 17-inch cathode-ray tube (CRT) monitor added an additional 75 watts. Newer, flat-screen LCD monitors use about half as much juice as CRTs.

In a sense, then, the PC isn’t a big juice hog. A microwave oven devours electricity at a rate of 750 to 1,100 watts, according to the U.S. Department of Energy.

PCs in power-saving standby or sleep mode have even less of a presence. In the Waterloo tests, they were draining 35 watts. That’s roughly equivalent to three clock radios.

But add up hours of standby time, and multiply that by the millions of computers in the world, and it is some serious electricity.

In fact, microchip maker Infineon Technologies AG, which is working on making electronics’ sleep modes more energy-efficient, estimates that a mere 1 percent decrease in standby power consumption would save the nation 360 megawatts — the equivalent of a medium-sized power plant. Put another way, 10 percent of an average home’s electricity consumption comes from machines of some kind sitting on standby, said Infineon spokesman Saswato Das.

Dell Inc., the world’s leading seller of PCs, has no official position on whether its customers should leave the machines running or not. Leaving computers on all the time doesn’t erode their performance, but it doesn’t appear that turning them off and on does either, because the reliability of key parts has improved significantly, spokesman Lionel Menchaca said.

“There used to be a bigger difference in terms of wear and tear when you power up your PC, but it’s not as much of an issue now,” Menchaca said.

After the tests at Waterloo, Manfred Grisebach of the university’s information systems and technology group pointed out that hard drives that never get shut down seem to live a long time. But, he said, so do drives that get shut off all the time.

“What we can’t say is which last longer,” he said.


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