Nope, but processors, especially larger ones, have pretty advanced power and clock management which allows them to deal with power envelope and thermal envelope

Nope, but processors, especially larger ones, have pretty advanced power and clock management which allows them to deal with power envelope and thermal envelope constraints. E.g. the two clocking and core voltage ladders in Xeon E5/E7 for AVX vs. non-AVX code. (Though this particular example is a bit of a sledge-hammer approach).