1. In a single integrated circuit (IC) chip having first and second functional circuits occupying distinct first and second regions of the chip, a system for selective regional temperature control, comprising: a first temperature sensor within the region of the first functional circuit and a first clock rate adjusting circuit supplying operational frequency to the first functional circuit; a second temperature sensor within the region of the second functional circuit and a second clock rate adjusting circuit supplying operational frequency to the second functional circuit; and logic control circuitry connected to the first and second temperature sensors and to the first and second clock rate adjusting circuits; wherein the logic control circuitry signals the first clock rate adjusting circuit to lower clock rate to the first functional circuit in response to increasing temperature sensed by the first temperature sensor, and signals the second clock rate adjusting circuit to lower clock rate to the second functional circuit in response to increasing temperature sensed by the second temperature sensor.