Using CPU Spy Android Apps you can found that on which cpu frequency your mobile runs more, and also you can diagnosis your mobile battery drain issues.
For example if your mobile’s battery drain too fast that is not normal you can see using cpu spy android apps that your mobile is going to deep sleep after you press power button or it is still awaken. Thereafter using spare parts android apps you can trace out which android apps or process stop your mobile to go on deep sleep.
Deep sleep is the state on which your mobile uses least cpu frequency and battery uses, it automatically off all the processes like 3G, wifi, syncing, display etc. but keep pinging with your cell tower so that you can get voice call and sms during sleep mode also.
Download this android apps directly from here CPU spy or from google play store.