FOR THOSE THAT DON'T WANT TO READ THE ENTIRE POST,THE OVERHEATING FIX IS INSTALLING THE KH3 MODEM (It's for the international S2 version,it's attached at the bottom of the post).
NO ROOT NEEDED!
Ok, so I got my samsung galaxy s2 a couple of months ago,and I had problems with signal loss for a couple of seconds from time to time , the person on the other end of a call could hear his eco during the call , but the biggest problem I had with it was that every time I turned on the internet 3g ,wifi or gps the phone would heat up to over 40 degrees celcius in less than 5 minutes (near the camera and the screen in the upper side).
After updating to ICS 4.0.3 LPQ the problem persisted, overheating, signal loss etc.
After some researching I found some people saying that the problem is not hardware related but software related...the modem to be more specific, I looked around and everybody was saying that THE BEST modem ever made for the samsung galaxy s2 is KH3 , so I went ahead and I installed it via odin and this is what I noticed:
-the phone stays at 25 degrees in standby, during a call at 28 degrees,and while on 3g,wifi or gps maximum 33 degrees celcius (it slightly feels warm).
-I have not had a single signal drop since installing it.
-Internet is faster,gps positioning is faster and call quality is allot better on both ends!
-My phone finished charging at 12 o clock midnight yesterday...its 12 o clock midnight where I am from,so after 24 hours since a full charge,I had a total of about 55 minutes of talk time , 10 minutes gps use, 15 minutes wifi and 10 minutes 3g I still have 75 percent of battery left!!!!!
So if you are experiencing any problems mentioned above I suggest you install the KH3 modem.
For those that are new and don't know how to install a modem,it's very easy and the entire process takes less than 2 minutes. NO ROOT NEEDED
Attached you will find ODIN and the KH3 modem , to install do the following, download the zipped file and unzip it in a folder, open odin and un-check "F. reset time" so that only "auto reboot" is checked ,then on the "Phone" button select the "modem.bin" file.
After that hold down the volume down+home+power button on your S2 until your phone powers down (and you can release)and then when the warning screen comes up press the volume down and the phone gets in to download mode,after that connect it to your computer and you should see a yellow 0COM6) (or something like that) come up,then all you have to do is click start and in 30 seconds your phone will bootup and when you go to setings and then about phone you should notice under "baseband" that it now says that you are running the kH3 version, I highly suggest that you install android 4.0.3 LPQ before you do this because it is a very stable upgrade witch brings new features to your phone and also I have not noticed a single bug with it.
Just to be clear, you can install this modem on any ROM , but I sugest you install the official ICS 4.0.3 LPQ version before installing this modem.
--------- Also,for those that experience signal drops (and this happens on all modems on certain carryers) go to menu,settings,more...,mobile networks,network mode and click "GSM only"..you won't have signal drops but unfortunatly choosing GSM only will limit your internet to EDGE only (not 3g or H+) ..so only do this if you experience signal drops. -----------
Also..and I have no idea why...with my previous radios my phone would get really hot while playing games (even if I had the internet or wireless off) ,it would get to 45 degrees,after flashing the KH3 modem...I played resident evil 4 (biohazard 4) and my phone stayed at 33 degrees celcius!!! ..and playing dead space..35 degrees!
Please come back with comments after flashing this modem.