Thermal Performance of Modular Microconvective Heat Sinks for Multi-Die Processor Assemblies

Abstract As processors continually seek greater computational output, the traditional single die processor configuration is giving way to emerging multi-die processor assemblies. As a result, dies of varying powers are spatially distributed in processor packages, causing local areas of high heat density and non-uniform temperature patterns. If not properly addressed, local hot spots may limit the total device operating power, increase leakage current to lower processor efficiency, and accelerate thermal induced semiconductor deterioration to reduce device lifetime. In this article, a modular microconvective heat sink (M2HS) is developed as a high effectiveness, high flexibility cooling solution for multi-die assemblies. Microconvective cooling, featuring optimized single-phase impingement cooling and effluent fluid flow control, provides high power density heat removal from localized heat flux zones on semiconductor dies. An AMD Threadripper 3960X is chosen as a multi-die test vehicle for the M2HS to test thermal performance in a liquid cooled experimental flow loop. Experimental results in overclocked thermal stress tests are presented, achieving power draws of up to 75% higher than the nominal processor TDP. Further, compared to a recommended product pairing of the CPU serving as a baseline heat sink, the M2HS showed a 51% improvement in CPU power draw performance. When operating at nominal, non-overclocked conditions, reduced temperature operation of the CPU using M2HS solutions resulted in a CPU efficiency increase of up to 10% compared to the baseline heat sink, providing opportunities for reduced PUE in large scale data centers. The study concludes that the M2HS shows promise as a high effectiveness, implementation-friendly cooling solution for emerging multi-die processor assemblies.