无风扇液冷 AI 服务器：高密度机架散热的下一步

High-density server racks exceeding 250 kW cannot rely on hybrid liquid and air cooling. At these power levels, a 70/30 liquid-air split leaves a substantial 75 kW air load that demands complex and costly air cooling infrastructure. The definitive solution involves near-total heat capture, where liquid cooling handles virtually all thermal loads, reducing air requirements to less than one percent and enabling completely fanless server operation. CoolIT currently implements these sophisticated cooling loops using modular coldplate blocks, a technology refined over six generations of fanless designs. The thermal design power of processors consistently increases with each new generation, causing heat loads to spread to previously air-cooled components like memory, networking, storage, and power modules. This escalation necessitates a more comprehensive cooling approach beyond just the central processing units. Shifting Thermal Dynamics in AI Servers For many years, the standard approach to server cooling was straightforward: actively cool the processor and allow ambient air to manage the remaining components. This equilibrium has profoundly shifted. As processor thermal design power rises, heat radiates outward, impacting surrounding hardware. Memory, network interfaces, storage drives, and power delivery units now generate enough heat to require their own dedicated liquid cooling solutions. Engineers developing next-generation AI servers must contend with motherboards where the demand for liquid heat capture intensifies with every new product launch. Beyond 250 kW per rack, air cooling becomes the bottleneck. Near-total liquid heat capture enables fanless AI server designs built for the next generation of computing. The thermal landscape of high-performance computing, particularly for AI applications, is rapidly transforming. Historically, peripheral components had sufficiently low thermal profiles that passive air cooling or general airflow within the rack was adequate. Today, the sheer power density of modern AI accelerators means these components generate significant heat, making them critical elements in the overall thermal management strategy. This shift mandates a re-evaluation of traditional cooling paradigms. The evolution of silicon technology dictates this change. More transistors packed into smaller spaces, operating at higher frequencies, inherently generate more heat. While processors remain the primary heat source, their influence extends, raising the ambient temperature within the server chassis. This elevated internal temperature then stresses other sensitive components, forcing engineers to integrate them into the liquid cooling loop. Addressing Diverse Component Cooling Needs Unlike processors, which typically present a flat, uniform surface for cooling, peripheral components come in various shapes, sizes, and mounting configurations. Each of these components possesses unique thermal limits. Some operate at temperatures below the processor’s case temperature, while others run hotter. This variability makes them susceptible to thermal design solutions optimized solely for CPUs and GPUs, highlighting the need for specialized cooling. Operators require bespoke solutions precisely matched to the individual component rather than a generic approach stretched across the entire board. CoolIT engineers deploy an extensive suite of tools to address these diverse thermal challenges. This toolkit includes conductive plates, vapor chambers, heat pipes, and thermal transfer plates, all designed to efficiently move heat from various components closer to the liquid cooling path. Riding coldplates facilitate the cooling of pluggable components, offering flexibility and modularity. Each of these solutions is specifically tailored to the characteristics and thermal requirements of the component it serves, ensuring optimal performance and longevity. Integrating these varied cooling mechanisms into a single, cohesive server loop presents a significant engineering challenge. The goal is to distribute coolant effectively across all components while ensuring ease of installation and maintenance. The reliability of connections, the efficiency of coolant routing, and the time required for loop assembly during rack integration are critical factors determining a design’s success in production environments. CoolIT constructs these loops using a foundation of proven modular blocks, providing operators with both enhanced performance and accelerated deployment within a unified solution. The Inevitable Shift to Total Heat Capture Rack power density continues its ascent, with projections reaching 1 MW. This escalating density consistently strengthens the argument for liquid cooling. A 70/30 liquid-to-air split proves adequate at lower densities. However, beyond approximately 250 kW per rack, this hybrid strategy becomes unfeasible. The remaining 30 percent air load translates to a substantial 75 kW within a single rack. Dissipating this immense amount of heat necessitates a parallel air cooling system whose cost, energy consumption, and physical footprint are largely unacceptable to most operators. Increasing rack density only exacerbates this disparity. As rack power continues to climb toward 1 MW, CoolIT’s modeling places full heat capture as the standard server design for flagship rack-scale products through 2028. The simpler and more energy-efficient approach involves capturing virtually all heat through liquid cooling, thereby reducing the air-cooled load to less than one percent of the total. Achieving a true 100 percent heat capture remains an extremely stringent goal in the strictest technical sense. Therefore, the practical and achievable target is near-total capture. This distinction holds importance for engineers who prioritize precision, yet the overall direction remains unequivocally clear. As power density increases, full heat capture transitions from a premium, specialized option to a fundamental requirement in mainstream server design. CoolIT’s internal modeling forecasts this approach as the standard for flagship rack-scale products through 2028. CoolIT implements heat capture solutions that scale toward 100 percent efficiency, utilizing modular coldplate building blocks. These components have demonstrated their effectiveness over six generations of fanless server designs. Engineering teams are actively developing designs for the ultra-high-density racks expected in the near future. As the thermal cascade expands across more components and rack densities continue to intensify, near-total heat capture emerges as the essential design principle for sustaining the operation of advanced AI systems.