Power management under light load

[Dmytro]

I hope it is the right place to place the topic.
I guess it worth to mention I read CRUST thread which is closely related to the topic. But it puts the device to sleep mode.
What I'm interested in is optimizing power drain for the device running under light to moderate load. For instance chatting or listening music.
My findings are:

• brightness scales from 0 to 8 with range 0 - 300 mA;
  
• cpu freq scales from 480 to 1152 KHz with range 300 - 600 mA;
  
• good findings end here
  
• software disable modem/Wifi gives nothing (hw kill switch gives ~120 mA for both);
  
• cpu cores online/offline gives nothing or even negative under load.
  

Conclusion: we can still save a lot
If CRUST can help to save from modem/Wifi turn off, does anybody know anything about cpu governor work? I mean to really save energy with core offline.