Development of a Thermal Test Vehicle for Server Memory Modules

Sammanfattning

The demand for data center computing is on the rise as a result of today’s widespreaduse of artificial intelligence. As new servers are developed to meet these demands, theirpower densities are getting higher than ever. The increasing data center power densitiesare starting to push the limits of existing cooling solutions, requiring new ones to bedeveloped. To prepare new cooling solutions ahead of time thermal test vehicles play acrucial role in emulating future hardware. This thesis is a design study of a Thermal test vehicle (TTV) that represents memorymodules commonly referred to as DIMMs. It is intended to emulate a complete server incombination with other TTVs. The goal is to provide a foundation for future work. A physical prototype containing four resistive DIMM TTVs was constructed, con-trolled by stepping down a fixed input voltage using a buck converter circuit. Each ofthe four DIMMs contain a thermocouple for temperature measurements and also mea-sure their current for estimating power dissipation. The sensors are read and the modulescontrolled from an ESP32 connected to a Raspberry Pi running Node-RED. The prototypes ability to control power and temperatures was evaluated and foundto be sufficiently accurate. The system was shown to draw 1 W of power when idle andthe efficiency increases with higher power levels. The current and voltage measurementswere very reliable and allowed for good power estimation. The temperature measurementwas shown to be slightly flawed, and the connectors that hold the DIMMs to the boardare prone to damage. It was concluded that while problems exist in its current state the TTV can still beused for the intended tasks and collect usable data doing so.