With the cost of electricity going up, like everything else, it is a cost to consider, particularly for those who leave computers on for long periods of time.
I have a device which can be plugged into the power, to measure how much electricity an appliance is using.
No doubt, different computers use different amounts electricity, and the same computer uses different amounts when used in different ways. Here is what I found with a couple of computers.
I use a 2.4 ghz desktop computer with a 21" crt monitor. This uses approximately 150 watts. When measured separately, the computer uses under 40 watts, and the monitor uses the rest.
I also have a notebook computer. This uses under 40 watts.
So no doubt, notebook computers use much less electricity than desktop computers with crt monitors.
I don't have a lcd desktop monitor, but I assume lcd monitors use less electricity than crt monitors.
In addition, I found the crt monitor uses over 30 watts when turned off, but still connected to the power. I suggest people using crt monitors turn off the power at the wall, when it is not in use.
I also found the notebook computer uses a similar amount of electricity whether turned on or off. Some of this may be charging the battery. However, I suggest people using notebook computers turn off the power to the computer, when the battery is charged, and the computer is not in use.
A similar thing happens with television. It uses a significant amount of power when connected to the power, but turned off. It is a good idea to turn off the power to the television, when it is not in use.
A similar thing happens with a number of other electrical appliances.
Many people are paying for electricity being used by appliances when they are turned off.
For those concerned about conserving electricity. By far the largest amount of electricity is used when heating or cooling. For example, hot water systems, heating the house, and air conditioning.