Mark Hull-Richter wrote: > On 5/29/07, Jim Perrin <jperrin at gmail.com> wrote: >> >> Watts = Volts x Amps. I usually use a sliding scale based on # of >> machines. >> > > I knew that (duh!). Watts = Volt-Amps IF the power factor is =1. Power factor is based on the reactance of the load. A purely resistive load has a PF=1. Google << watts vs volt-amps >> for more info, e.g. http://www.vabiomed.org/documents/tech0003.htm. The power supplies I have measured in servers have a power factor close to 1. But I have measured consumer machines with a power factor considerably different than 1. That cute little power meter mentioned earlier in this thread (the "Kill-a-Watt") will measure it. Dan