All "power" that is used turns into heat so this is a semantic detail that both of these terms will be related. If you measure heat you are also measuring Watts used to create that heat, and vice versa.
This is conservation of energy, otherwise where does the power go? Certainly not to mechanical work or to other forms of energy such as light.
To answer what I think is your question about efficiency, you can take a look at some of the power charts and compare the Idle power draw versus the peak power draw to get some sense of the energy for overhead of the CPU maintenance versus computational work.
Excellent point let me re-phrase the question:
Roughly how much power is dissipated through impedance (therefore not doing any useful work , in regards to the cpus purpose), relative to the amount power input into a cpu in general?