Energy consumption vs % utilization?

Wed Oct 27 00:57:26 UTC 2004

On Tue, 26 Oct 2004, David Lesher wrote:

>
> Speaking on Deep Background, the Press Secretary whispered:
> >
> >
> > You should be able to pick up simple current / wattage meter from local
> > hardware store for $20 or so. That will tell you that on a modern
> > dual-CPU machine the power consumption at idle CPU is about 60% of peak.
> > The rest is consumed by drives, fans, RAM, etc. As wattage the
> > difference is 100-120W (50-60W per cpu)
>
> Bogus data alert....
>
> A ammeter will tell you amps. But in the world of switcher power
> supplies, that does not beget watts. [Why? is an exercise for
> the student. Start with "power factor" and "VARS" and worry about
> asymetric loads...]
>
> If you want to talk watts, as you must to worry about HVAC,
> or really watt-hours... acquire a power company type meter - in
> glass with a whirlygig. Put it in a meter box with plugs. [See
> your local eletrical wholesaler..]
>
> (The rotating disk watthour meter is amazingly accurate under
> almost any kind of load waveform. Only time-of-day metering has
> spurred the utilities to replace them.)
>
> Plug the machines into it; it into the wall. Note the numbers
> and the time, and come back in 24Hours.

Instead of doing all this, just buy a Kill-A-Watt meter for about $30, and
get an instant reading of Watts, Amps, VAs, power factor, and KWH.

K