Intel Power Gadget

Estimating the power or energy usage of your computer's CPU is not something that most full-featured system utilities can perform or are not able to complete this action with a high degree of accuracy.
Developed with the interests of developers that require a precise estimation of CPU power in mind, Intel Power Gadget is the official power usage monitoring utility for all Intel Core processors, starting from the 2nd generation and up.
Before we get started, it should be noted that the utility does not work with Intel Atom processors.

Lightweight app that can be installed with the minimum amount of effort

The application can be quickly deployed on your computer once it undergoes a streamlined installation process. Subsequently, upon first launching the app, you are greeted by the app's compact graphical user interface.
Getting to grips with this Intel-vetted app should not pose any kind of problems, since everything is thought-out to be as straightforward as possible. All the panels from the app's GUI have dedicated analog reading sections and real-time graph sections, as well.

Accurate readings about your computer's CPU power usage on the desktop

This said, in the top panel, the app displays the current power consumption and the average power limit. Underneath, you can get an accurate description regarding the current and the graded  CPU frequencies, while the bottom panel allows you to view the current and maximum allowed package temperature.
Intel Power Gadget's Options window is just as simple as the rest of the app, with just a few available features on tap. You can choose to setup the app to automatically add time-stamps to the file names at run time, you can resize the GUI up to 300% percent, choose the screen update and the log sampling resolutions with increments of milliseconds.
Please note that the Package ID option actually allows you to pick which exact processor package is going to be monitored. Also something that it worth mentioning is the fact the app saves all your CPU power consumption recordings to log files that can be generated at any location of your choosing.

Useful tool for monitoring the power usage of Intel processors

By packing drivers and libraries specially designed for Intel processors, it is safe to say that if you are looking for an accurate, if not the most accurate, tool for reading your computer's processor power usage then Intel Power Gadget is probably your best choice.