how much power does a desktop PC consume in a month if it's always on?

Hi micromatt,

There is, of course, a wide range of "desktop PCs", but I presume you
will be happy with a typical figure.

The University of Waterloo has measured the power consumption for
their typical configuration: a Pentium 4 1.7GHz machine:

"During boot, power in watts is close to 110w; during idle with no
power management, close to 60w; during full power saving with no hard
disk spin and machine in sleep mode, 35w."

"PC Power Consumption"
http://windows.uwaterloo.ca/PC_Power_Consumption.htm

It's also necessary to consider the power consumption of the monitor.
The same page states that a Sony 17" monitor consumes 75w when in use,
and that when power saver mode kicks in the power consumption is
negligible.

They conclude that "a typical PC and monitor does not consume more
than 175 watts of energy at its highest rate. At night time when your
PC is 'sleeping' it only consumes 35 watts."

If we assume that a PC is "working" for eight hours a day and
"sleeping" for 16 hours a day, the average consumption would be just
under 82 watts.

There are 720 hours in a 30-day month, so this typical PC would
consume just under 60 kilowatt-hours per month. If you pay 5 cents per
kilowatt-hour, that's $3 per month. If you pay 10 cents per
kilowatt-hour, that's $6 per month.


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Regards,
eiffel-ga

amazing...i'm very impressed by the thorough, detailed, and well-cited answer