Influence of component arrangement on thermal management in immersion-cooled server boards

Effective thermal management is recognized as a key factor for ensuring the reliability, performance, and energy efficiency of high-density immersion-cooled server boards. In this study, a systematic investigation is conducted to examine the impact of component arrangement on the thermal-hydraulic behavior of single-phase immersion-cooled servers, considering three CPU layouts (transverse, longitudinal, and diagonal), three memory module configurations (spaced, compact, and distributed), and three dielectric coolants (EC-110, FC-40, and mineral oil) over a wide range of operating conditions. Results show that CPU layout dominates thermal behavior: transverse arrangements achieve the lowest temperatures and highest uniformity, longitudinal layouts experience pronounced thermal cascade, and diagonal layouts offer an optimal compromise with near-perfect CPU temperature uniformity and significantly reduced pressure drop. Memory module arrangement influences performance in a layout-dependent manner, with spaced, compact, or distributed configurations optimizing local heat transfer and suppressing thermal interaction between components. Increasing flow rate consistently reduces peak temperatures, while coolant properties critically impact thermal-hydraulic behavior, with EC-110 providing superior thermal stability, FC-40 enhancing uniformity, and mineral oil requiring higher pumping power. Importantly, minimum flow rates necessary for safe operation vary strongly with layout, highlighting geometric optimization as a more energy-efficient strategy than increased flow. This study demonstrates that strategic CPU and memory placement, particularly in transverse or diagonal configurations, enables lower peak temperatures, improved thermal uniformity, and reduced energy consumption. The findings provide actionable design guidelines for next-generation immersion-cooled data centers operating under increasingly high-power densities.