Modern integrated circuits generate very high heat fluxes that can lead to a high temperature, degrading the performance and reducing the life time of the device. Thermal simulation is used to prevent this kind of issues, and many models were introduced in recent years. However, their validation is challenging: it is either based on established simulators (with reduced accuracy), or requires to produce a specific test chip with several thermal sensors. In this paper we propose a methodology and measurement setup that uses existing commercial processors to validate thermal models. We use infrared thermography and low-cost thermoelectric cooling, avoiding the issues of mineral oil setups used in previous works. We show how our approach was used to validate two thermal simulators.