Single-Phase Liquid Cooling of a Quad-Core Processor

Multicore microprocessor chips have emerged as an industry standard in recent years and have enabled Moore’s Law to be sustained when one considers the collective performance achieved by multiple cores. The industry has favored floor plans that use identical or symmetric layouts of individual cores in a linear array or a two-dimensional (2D) array, oblivious to the non-uniform heat dissipation within each core. Such non-uniform heat dissipations have hot spots within each core that must be aggressively cooled to avoid temporary or permanent device failures that can result from high temperature gradients. This paper evaluates alternative core layouts and microchannel configurations of a single-phase liquid cooling system for multi-core chips. We first examine the use of different planar flow patterns in microchannels for a realistic quad-core processor with non-uniform energy dissipation within each core. The direction of the flows in the microchannels is varied to achieve minimum hot spot temperatures on the die. A symmetric layout of the four cores with minimum achievable hot spot temperature is then selected and subjected to impingement flow. We establish the thermal efficiency of the optimized core floor plan compared to the traditional floor plan in a quad-core design and show that impingement provides the most efficient cooling solution compared to microchannels with planar flows for the same pressure difference.