Personally, I think they're a placebo effect, but I never gone in depth to do any real comparisons so I could be wrong. And the M8 has a good enough battery to where I don't consider needing a battery saver.
I'm using Green Power for a while now but lately I have been thinking that it might not be needed anymore.
What are your thoughts and what are you using to save battery.
I ran Qualcomm's Battery Guru app customized for our CPU on my Rezound and now my M8, but ultimately decided that I would just run in standard powersave mode. My kernel lets me undervolt and overclock, so I get decent battery life coupled with fairly good performance without ruining any other battery software.
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