I'd so some practical research to answer those questions. There are nice inexpensive power meters that show exactly how much Watt a device connected trough it consumes. Most even let you enter the price per kWh, and show how much using it for one hour costs.
Much better than theory.
I'm doing research on power usage by desktop,laptops,... and I got some questions.
Some desktops work with adapters (just as notebooks do) and it got me wondering...is the power stated on the adapter the maximum that the device can consume? I.e. adapter says 200W, does that mean that this device can consume a maximum of 200W ? Also is power usage constant? Logically one would say that a low burden on a device will also lower the power usage but is this in fact true?
And do the answers to the previous questions apply for devices without an adapter?
Thanks in advance