Data center proliferation has been increasing significantly around the world attributed to growth in technologies such as the Internet of Things (IoT), bitcoin mining, and high-performance computing (HPC). A direct consequence of these developments is an enhancement in processing units and a corresponding rise in CPU and GPU power densities. Limitations of air cooling to dissipate increasing power densities in processors have compelled the researchers to move toward better and efficient liquid cooling solutions. In an earlier study, a custom-made mini-rack with liquid-cooled 2OU (open rack Unit) web servers were tested for comparison of centralized and distributed pumping with constant flow rates at the server level. The effect of higher inlet temperature in terms of IT power, cooling power consumption, and CPU temperature was reported along with a comparison of centralized versus distributed pumping. In this article, the same 2OU server is used to show the effect of variable flow rate on server thermal performance. The parameters monitored for performance quantification are the core temperatures, dual in-line memory modules (DIMM) temperatures, and platform controller hub (PCH) temperature. These parameters were reported by varying the CPU power consumption, coolant inlet temperatures, and coolant flow rates by controlling the distributed pumps. The server was fully enclosed with no outside air intake where the CPUs were cooled by cold plates and the rest of the components with internally recirculating air. The results obtained from the experiments were compared with the results obtained from a previous study where the effect of the variable flow rate was ignored. A full-factorial design of experiments (DoE) was designed using Minitab 19 to analyze the results statistically.

中文翻译：

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在服务器级动态控制冷却液流量的液冷服务器节能比较研究

由于物联网（IoT），比特币挖掘和高性能计算（HPC）等技术的增长，数据中心在世界范围内的增长已大大增加。这些发展的直接结果是处理单元的增强以及CPU和GPU功率密度的相应提高。为了消除处理器中不断增加的功率密度而进行的空气冷却的局限性迫使研究人员转向更好，更高效的液体冷却解决方案。在较早的研究中，测试了带有水冷式2OU（开放式机架单元）Web服务器的定制微型机架，以便在服务器级别比较恒定流量下的集中式泵和分布式泵。入口温度升高对IT功率，冷却功率消耗，报告了CPU温度以及集中式泵与分布式泵的比较。在本文中，使用相同的2OU服务器来显示可变流速对服务器热性能的影响。监控性能量化的参数是核心温度，双列直插式内存模块（DIMM）温度和平台控制器中枢（PCH）温度。通过控制分布式泵来改变CPU功耗，冷却液入口温度和冷却液流速来报告这些参数。服务器完全封闭，没有外部进气口，在这里，CPU由冷板冷却，其余组件由内部循环空气冷却。从实验中获得的结果与从先前的研究中获得的结果进行了比较，在先前的研究中，可变流速的影响被忽略了。使用Minitab 19设计了全要素实验设计（DoE），以对结果进行统计分析。