How could software know what power is being used by all components in your computer? Like your harddrive is going to tell? Like your power supply (who has its own inefficiency) is going to tell? There is no logic that sends this information in a way usable by software. Software can only see what hardware you have and guess what the usage could be; not measure.
It can measure voltage of your CPU though, and GPUs have some info about this as well. But that's it. Buy a real power meter, and make sure to get one that supports Power Factor Correction (PFC) or it will give false readings!