Integrated Silicon Microfluidic Cooling of a High-Power Overclocked CPU for Efficient Thermal Management

Abstract

The stagnation of Dennard scaling along with the move towards heterogeneous 2.5D and 3D ICs is increasing the thermal design power (TDP) envelopes of general-purpose CPUs. With conventional cooling approaches such as air-cooling and cold plates, it is challenging to meet these increased requirements. Moreover, these increasing cooling requirements necessitate larger thermal management overheads in datacenter settings. All these trends point towards the need for a more aggressive and efficient cooling solutions. Monolithic microfluidic cooling, where silicon micropin-fins or microchannels are etched directly into the backside of the functional silicon, has shown great potential in this regard. In this work, we use micropin-fins etched directly on the back of an Intel Core i7-8700K CPU and overclocked it to dissipate up to 215W of power while being cooled by room temperature de-ionized (DI) water. We demonstrate up to 44.4% reduction in junction-to-inlet thermal resistance while using only 0.3× of volumetric coolant flow per Watt of power dissipated in the CPU compared to a conventional cold-plate. Furthermore, we demonstrate higher sustained core frequencies even when being cooled with elevated inlet temperatures, showing the potential for more efficient datacenter operations without the need for expensive and energy intensive refrigeration loops. The scalability towards heterogeneous 2.5D and 3D devices is also discussed. These results point towards a more scalable, efficient cooling solution, which can unlock higher power, more efficient compute systems, while minimizing the environmental impacts by reducing the thermal management overheads.