A METHODOLOGY FOR THERMAL CHARACTERIZATION OF HIGH-POWER LIQUID-COOLED SERVERS

Effective cooling is crucial for high -power liquid-cooled servers to ensure optimal performance and reliability of components. Thermal characterization is necessary to ensure that the cooling system functions as intended, is energyefficient, and minimizes downtime. In this study, a proposed methodology for thermal characterization of a high -power liquid-cooled server/TTV [server and TTVs (thermal test vehicle) are used interchangeably] is presented. The server layout includes multiple thermal test vehicle setups equipped with direct-to-chip cold plates, with two or more connected in series to form a TTV cooling loop. These cooling loops are connected in parallel to the supply and return plenums of the cooling loop manifold, which includes a chassis-level flow distribution manifold. To obtain accurate measurements, two identical server/TTV prototypes are instrumented with sensors for coolant flow rate and temperature measurements for every TTV cooling loop. Four ultrasonic flow sensors are installed in the flow verification server/TTV to measure the coolant flow rate to each TTV cooling loop. In the thermal verification server, thermistors are installed at the outlet of each GPU heater of TTV cooling loop to log temperature measurements. The amount of heat captured by the coolant in each TTV cooling loop is subsequently estimated based on the flow rates determined from the flow verification server. This methodology enables precise characterization of the thermal performance of high -power liquid-cooled servers, ensuring optimal functionality, energy efficiency, and minimized downtime.