How to control fan speed and disable discrete graphics in Dell laptop

[reneo]

​I have the Dell laptop Inspiron 7520. It has integrated Intel 4000 and AMD 7730M discrete graphics. I can successfully install Sierra on it, the fan is maximum speed most of the time, it might stop for a few seconds when cooler and then go maximum speed again. How do I disable the AMD 7730M discrete graphics to lower the overall heat? And then how do I control the fan to make it less aggressive in speed? I have tried Mac Fan Control, it did not see the fan at all. I have tried linux, it could disable the discrete graphics and has an utility called i8kmon that lowers the fan speed, so I know it is possible to control the fan by software means. The problem is how on Hackintosh. Help me!