If your device is hot enough to emit gasses you can smell, you are done cooked to some degree. Unless it was the battery emitting the smell.

I have played MAME and PSX4ALL for over an hour with no heat issues at 800mhz. I can not distinguish a heat difference from 600mhz. That being said, I will not clock beyond 800mhz. Happy with the current speed, so no need to gamble further.