A system includes a plurality of processor cores and a power management unit. The power management unit may be configured to independently control the performance of the processor cores by selecting a respective thermal power limit for each of the plurality of processor cores dependent upon an operating state of each of the processor cores and a relative physical proximity of each processor core to each other processor core. In response to the power management unit detecting that a given processor core is operating above the respective thermal power limit, the power management unit may reduce the performance of the given processor core, and thereby reduce the power consumed by that core.