Pretty sure its automatic. Question is wether or not you have to Enable / Disable the new Turbo Boost Technology 2.0. I know the old turbo boost technology is automatically on / running via settings in the BIOS, and you cant really control it. You can turn it off / on in the BIOS Settings though. The technology will read temperatures of the CPU, and then over clock cores / take cores out to give the best performance.
The 2.0 Technology is used in the new Intel Sandybridge CPU's which Im going to make a post on now / shortly.