My machine is a Lenovo G580 with these specifications:
- Processor: intel core i7 3520M
- Graphics: intel core HD graphics 4000 + nvidia Geforce 710M
- RAM: 6GB
I'm on ubuntu 13.04 64 bits and I've set up bumblebee.
The computer gets too heat (more than 70ºc) when I leave the cpufreq in "ondemand" mode and it shouldn't since I'm not doing too intensity-CPU stuff.
I think that it's due to excessive use of intel hd graphics for rendering the screen, because if i put the frequency to 2.9GHz, the temperature is still ok; but I leave the cpufreq to switch the cpu freq, it warms up.
A workaround could use the nvidia graphics card for unity and firefox (things I've always opened), something I don't know how to do it.
Also, i would like to know if, eventually, the optimus nvidia technology (to change automatically from integrated to dedicated GPUs depending on the current graphics/video use.) it's going to be supported in Linux, either proprietary or open source way.
I'm sure the discrete graphics-card, the nvidia Geforce 710M, must be responsible for your heating problem. By using bumblebee you may have triggered it. I recommend using the nvidia-prime driver (activate in "system settings -> software & updates -> additional drivers -> nvidia-331") and to choose manually between integrated and discrete graphics, which is possible within "nvidia-settings->PRIME Profiles". By turning the nvidia card off your laptop will stay much cooler.