Provide a throttling option for the Rendering process

Running a Skylake 8-core and getting an overheat warning whenever I run the rendering process. Per your suggestion I adjusted the CPU affinity mask....definitely helped but still on occasion one of the cores that I specifically masked out kicks out the overheat warning. The rendering is extremely fast on this box so a throttle to cut the CPU usage by a third or a half really would not make much of a difference in terms of waiting time. Thx.