To get to the efficiency calculator, open command prompt as administrator (Start – CMD – Right click and select Run as administrator) and type powercfg –energy and hit Enter.
Windows 7 will now observe your system looking for ways to improve power efficiency. It will then bring out the results in an HTML file in the System32 folder (C – Windows – System32 – Energy-report.html). Open the file in your browser and look for the errors, warnings and other details.
