IEEE Spectrum breed · Technology

Fanless AI Servers Achieve Near-Total Heat Capture

As AI server racks approach and exceed 250 kW, traditional hybrid liquid-air cooling becomes insufficient. This necessitates a shift towards near-total heat capture using liquid cooling to enable fanless server designs.

At densities beyond 250 kW per rack, the remaining air cooling load becomes unmanageable, requiring costly and complex systems. Near-total heat capture by liquid cooling reduces the air load to below 1%, allowing servers to operate without fans.

Historically, cooling focused primarily on processors. However, rising processor thermal design power (TDP) is now causing heat to spread to memory, networking, storage, and power components, requiring them to be liquid-cooled as well.

Cooling these diverse peripheral components, which vary in shape, size, and thermal requirements, demands specialized solutions beyond standard CPU/GPU coldplates. Engineers use conductive plates, vapor chambers, and heat pipes to transfer heat from these parts to the liquid cooling loop.

Integrating these varied cooling solutions into a single, reliable server loop is crucial for production deployment. CoolIT utilizes modular coldplate blocks, proven over six generations, to create these integrated loops, balancing performance with ease of installation.

The increasing rack power density, projected to approach 1 MW, makes full heat capture the most efficient solution. A 70/30 liquid-air split becomes unviable past 250 kW, making near-total liquid capture the standard for high-density racks.

CoolIT's approach uses modular coldplate building blocks to scale heat capture towards 100%. This design is expected to become the standard for flagship rack-scale products through 2028 as component heat cascades and rack densities continue to rise.

AI-samenvatting op basis van de bron.