Investigation on Performance Difference Between Air and Liquid Close Loop Heatsink in a 1U Server

Thermal challenge increases dramatically with the increasing processors Thermal Design Power (TDP), especially in high density system with limited space for thermal solutions. Open loop liquid cooling solution is one option to support high power processor. However some users request to keep the same platform form factor to support next generation processor. Enhanced Volume Air Cooling (EVAC), Liquid Assisted Air Cooling (LAAC), Loop Heat Pipe (LHP)and Loop Thermosyphon Heatsink (LTSH)are widely deployed by users. Comparison of thermal performance using these four different cooling technologies in Intel 1U server with board S7200AP is presented in this paper. Thermal experimental data shows that heatsink resistance Psi ca varies from 0.107 C/W to 0.204 C/W with these four different solutions. Simulation modeling with Computational Fluid Dynamics (CFD)tool as Flotherm is calibrated for each individual technologies. The difference in heat exchanger size, fin exchanger surface, system boundary condition all lead to thermal performance difference besides different technology. Therefore, simulation modelling is adjusted to show the capability limitation and true difference for each technology under same heat exchanger keep out zone (KOZ)and system boundary in 1U form factor.