Evaluation of Graphene-Enhanced Thermal Interface Material in Air and Immersion Cooling Systems

This study presents a detailed performance evaluation of a graphene-enhanced thermal interface material (TIM) conducted at RISE ICE Data Center. Tests were performed on Open Compute Project (OCP) Leopard servers using three different TIMs: conventional thermal paste, graphene-enhanced thermal pad GT90 from SHT Smart High Tech AB (SHT), and indium foil. Three sets of experiments were conducted: (1) air cooling with default chassis fan control in a bespoke server wind tunnel, (2) air cooling with controlled, fixed fan speeds and different heatsink mounting pressures operating in the wind tunnel and (3) immersion cooling tests with two coolant flow rates at fixed inlet temperatures. Results indicate that graphene-enhanced TIM and thermal paste exhibit similar performance in experiment (1), whereas indium foil TIM tests showed the undesired effect of increased CPU temperatures. In experiment (2), servers equipped with graphene-enhanced TIM showed lower CPU temperatures in comparison to the servers equipped with Indium foil TIM. In experiment (3), immersion cooling resulted in lower CPU temperatures overall, with the graphene-enhanced TIM again providing lower temperatures than indium foil at a similar mounting pressure. The findings suggest that the interfacial thermal conductivity and material compatibility of the GT90 TIM contribute to an improved performance in the tested immersion cooling system as well as the importance of mounting pressure.