Often I've wondered about standby mode power consumption. How much electricity it uses when my computer is in sleep mode? Since my computer (a tower desktop with two LCD monitors) is several years old it takes a while to boot up so I like to leave it in standby mode when I can.
To test the standby mode power consumption of my computer I got a P3 International Kill-a-Watt meter for about $21 online. The Kill-a-Watt power meter plugs into the wall and then the appliance plugs into the meter. The Kill-a-Watt meter has an LCD screen to tell you how much electricity was used in that time period.
Here's what I found (cost per KWH in Maryland is 10.28 cents):
Table of Sleep Mode Power Consumption
The standby mode power consumption is just a bit more than leaving the computer plugged in but off. So I can use standby mode without any additional cost.
While I'm away for more than 8 hours it makes sense to turn the computer off at the power strip. At this point no electricity is being used. This is usually when I am done using the computer in the evening.
Note - if you have power supplies plugged directly into the wall they will be using electricity (feel them, they'll be warm). The power strip allows you to turn them off completely. This goes for stereo systems, power tools, etc.
