Tab stays on 216mhz instead of Deep Sleep I am using Samsung Galaxy Tab 10.1 and I have installed Cpu SPY. I have noticed that when I leave the tab in the night, WiFi OFF, flight mode on, it does not go to Deep Sleep but stays on 216Mhz.
I guess it is an app or something, however I do not know how to investigate this.

I run 4.0.4 stock, rooted.

What can I do to have the device on Deep Sleep the time that it stays on 216Mhz?
To have your device in Deep Sleep, you need to find out what applications are running and causing a wakelock that doesn't let the CPU go bellow 216MHz, thus preventing the device from entering into Deep Sleep mode.

I can recommend BetterBatteryStats by Sven Knispel available from Google Play Store:


  A high battery drain is often a limiting factor for a great user experience.
  With BetterBatteryStats you can analyse the behavior of your phone, find applications causing the phone to drain battery while it is supposed to be asleep and measure the effect of corrective actions:
  
  
  Spot drainers based on detailed information about the root cause
  Use the online Knowledge-Base to find how to reduce or remove the wakelocks
  measure the effect of actions to reduce drain
  detect changes in the awake/sleep profile and quickly find the causes (rogue apps)
  
  
  In other words BetterBatteryStats helps you to get the best out of your Android smartphone.


After finding out the applications that are causing your problem. Don't forget to disable BetterBatteryStats.