Fan Control and GPU temperature

[juliandroms]

Does anybody know, does fan control control the speed of the fan (the temperature sliders in the app) based on the temperature of the CPU or is the temperature of the GPU also factored in? Does anyone know how a MacBook keeps the GPU control - what if the GPU is hot but the CPU is not hot? Does the MacBook normally control fan speed not based just on CPU temperature, but also GPU temperature.

I have a Macbook Air and I am more concerned about GPU temperature, not CPU temperature. I just had to fix my Macbook Air logic board by reflowing the GPU chip. I'd like to keep the GPU chip on the cool side to prevent this from happening again.

Thanks.