The increasing integration of high performance processors and dense circuits in current computing devices has produced high heat flux in localized areas (hot spots), which limits their performance and reliability. To control the hot spots on a central processing unit (CPU), many researchers have focused on active cooling methods such as thermoelectric coolers (TECs) to avoid thermal emergencies. This paper presents optimized thermoelectric modules on top of the CPU combined with a conventional air-cooling device to reduce the core temperature and at the same time harvest waste heat energy generated by the CPU. To control the temperature of the cores, we attach small-sized TECs to the CPU and use thermoelectric generators (TEGs) placed on the rest of the CPU to convert waste heat energy into electricity. This study investigates design alternatives with an analytical model considering the nonuniform temperature distribution based on two-node thermal networks. The results indicate that we are able to attain more energy from the TEGs than energy consumption for running the TECs. In other words, we can allow the harvested heat energy to be reused to power other components and reduce cores temperature simultaneously. Overall, the idea of simultaneous core cooling and waste heat harvesting using thermoelectric modules on a CPU is a promising method to control the problem of heat generation and to reduce energy consumption in a computing device.