I have a 32GB Galaxy S3 that I purchased from Rogers in October that has started acting up in the last month. For whatever reason, the phone will, on an intermittent basis almost go haywire.
When it does this, it starts RAPIDLY draining battery. Normally this phone uses up about 1.2%/hour when sleeping, but when it's flaking out, it jumps to 11.5% or so. I'm running both Better Battery Stats and GSAM Pro. BBB seems to indicate that when this is happening the phone isn't sleeping. GSAM Pro indicates that the majority of battery drain is coming via the "Android System" and "Kernel (Android OS)" apps. So this is something either going wrong with the OS or one of the apps that are added into the OS by Rogers.
The *only* way this rapid draining seems to stop is if I do several cold boots in a row.
Currently the phone is running 4.1, from the update in December. I'm sincerely hoping that 4.1.2 gets to us soon. The American carriers, which run the same model as ours have all started pushing this update out to their customers in the last few weeks. The Canadian carriers, I think, are the last ones to proceed with the update.
I *have* done a factory wipe, back when the phone was upgraded to 4.1 in December. I've been holding off doing a new one because I don't want to have to set everything up again if I wipe it now, and then the phone gets the 4.1.2 update in a few weeks.
U can backup ur data with titanium backup and then restore it after the reset. Alternatively you can mod ur phone, which will void ur warranty, and install a custom Rom. Mine suddenly starts drawing battery as well sometimes and gets warm, CPU is definitely working. A reboot cures it.