What is Thermal Management?

What Is Electronic Thermal Management in AI Servers?

 

AI servers use high-power CPUs and GPUs to process demanding workloads. These components generate large amounts of heat in a small space. If this heat is not removed effectively, the servers may become unstable, reduce their processing speed, or require more energy for cooling.

 

Electronic thermal management covers the methods used to move heat away from server components and release it outside the system. As chip power and rack density increase, this becomes a larger challenge for both server and data center design.

 

This article explains how heat is transferred in AI servers, compares common cooling methods, and introduces how CreAlien W2PC uses DI-water two-phase cooling to support high-density AI workloads.

 

What Is Electronic Thermal Management in AI Servers?

 

Electronic thermal management in AI servers refers to the design of the cooling paths that remove heat from high-power components and release it outside the system. It involves more than preventing a chip from overheating. The entire path must work together, from the chip package and thermal interface material to the heat sink or cold plate, the cooling fluid, and the equipment that rejects heat outdoors.

 

The main goal is to keep CPUs, GPUs, memory, power components, and other heat-generating parts within their allowable operating temperatures. Effective thermal management helps servers maintain stable operation under sustained AI workloads while reducing unnecessary cooling energy.

 

How Does Heat Move Away from AI Server Components?

 

Heat must travel through several stages before it can leave an AI server and the surrounding facility. A typical path may be:

 

Chip → thermal interface material → heat sink or cold plate → air or cooling fluid → heat-rejection equipment → outdoor environment

 

Two related concepts help explain how this process works.

 

• Conduction, Convection, and Radiation

 

Conduction occurs when heat moves through solid materials. For example, heat travels from a CPU or GPU through thermal interface material to a heat sink or cold plate.

 

Convection occurs when moving air or liquid carries heat away. Server fans create airflow across heat sinks, while liquid-cooling systems circulate coolant through cold plates and heat exchangers.

 

Radiation transfers heat as electromagnetic energy. It occurs in electronic systems, but it usually plays a smaller role than conduction and convection in AI server cooling.

 

• Sensible Heat and Latent Heat

 

Air cooling and single-phase liquid cooling mainly remove heat through sensible heat. As air or liquid absorbs heat, its temperature rises before it carries that heat away.

 

In contrast, two-phase cooling relies on latent heat during a phase change. When a liquid changes into vapor, it can absorb a large amount of heat without a corresponding large rise in temperature.

 

What Cooling Methods Are Used for AI Servers?

 

AI servers can use different cooling methods depending on component power, rack density, deployment environment, and facility infrastructure. The following approaches differ mainly in how they collect heat from CPUs and GPUs.

 

• Air Cooling

 

Air cooling uses heat sinks and server fans to move heat away from components. The fans push air across the heat sinks, and the warm air is then removed from the server room by the surrounding cooling system.

 

This approach remains suitable for many AI servers. However, higher component power can require faster fan speeds and greater airflow, which may increase fan energy use and noise.

 

• Single-Phase Direct-to-Chip Liquid Cooling

 

In single-phase direct-to-chip liquid cooling, coolant flows through cold plates attached to CPUs or GPUs. The coolant absorbs heat and becomes warmer as it passes through the cold plates. It then transfers the collected heat to a facility water loop or other heat-rejection system through a coolant distribution unit or hear exchanger.

 

This approach removes heat closer to the source than air cooling and reduces the amount of heat that must be carried by room air.

 

• Two-Phase Direct-to-Chip Liquid Cooling

 

Like single-phase direct-to-chip liquid cooling, two-phase direct-to-chip liquid cooling captures heat close to the CPUs and GPUs. However, it uses a liquid-to-vapor phase change to absorb heat. The vapor later releases the heat as it condenses back into liquid and returns to the cooling loop.

 

Because phase change uses latent heat, this approach can remove high heat loads without relying only on a large temperature rise in the cooling fluid. The working fluid and system design vary by technology, so two-phase cooling systems may operate differently from one another.

 

As AI chip power and rack density continue to increase, the limits and infrastructure requirements of each approach become more important.

 

Why Are AI Servers Becoming Harder to Cool?

 

Cooling becomes more difficult when more heat is generated within the same server or rack. This is increasingly common in AI deployments, where CPUs and GPUs must process demanding training and inference workloads over long periods.

 

• Higher Chip Power

AI processors can generate far more heat than components used in conventional servers. The cooling system must remove heat continuously to prevent thermal throttling or instability.

 

• Greater Heat Density

More high-power GPUs can be installed in the same rack, concentrating heat into a limited space. The challenge is not only the total cooling load, but also how quickly heat must be removed from each component.

 

• Higher Cooling and Infrastructure Demands

As heat loads rise, air cooling may require higher airflow and fan speeds. Liquid-cooling systems may reduce the heat handled by room air, but some designs also depend on chilled-water loops, chillers, cooling towers, and related facility equipment.

 

These conditions do not make one cooling method suitable for every deployment. They make it more important to select a cooling architecture that can remove the required heat without creating unnecessary energy use or infrastructure demands.

 

Why Can Two-Phase Direct-to-Chip Cooling Support Higher Heat Density?

 

Air cooling, single-phase liquid cooling, and two-phase cooling all remove heat from AI server components. Their main difference is how the cooling medium absorbs and carries that heat away.

 

 

In air cooling and single-phase liquid cooling, a higher heat load usually means moving more air or liquid through the system, or allowing that air or liquid to become hotter.

 

Two-phase cooling works differently. When the liquid changes into vapor, it can absorb additional heat without needing a large rise in its own temperature. This can reduce the airflow or the coolant temperature increase needed to handle the heat from high-density AI servers.

 

The collected heat still needs to be released outdoors. The condenser and other heat-rejection equipment must therefore have sufficient capacity to meet the server’s total cooling load.

 

The following section explains how CreAlien applies this principle through its DI-water two-phase cooling system.

 

How Does CreAlien W2PC Support High-Density AI Server Cooling?

 

CreAlien W2PC is a DI-water two-phase cooling system for high-power CPUs and GPUs. It uses a sealed loop under negative pressure. This lowers the boiling point of the DI water to approximately 45ºC.

 

• Capturing Heat at the Chip

 

DI water flows through cold plates attached to the CPUs and GPUs. When it absorbs heat from the components, part of the water changes into vapor.

The vapor carries this heat to the condensation side of the system. There, it releases the heat and turns back into liquid. The liquid then returns to the cold plates and repeats the cycle.

 

The heat follows this path:

Chips → W2PC DI-water loop → heat-exchange equipment → outdoor environment

 

• Supporting Chiller-less Cooling

 

Many cooling systems use a chiller to produce low-temperature chilled water before they can remove heat from the servers. W2PC does not require this chilled-water step.

 

Because its DI-water loop operates at approximately 45ºC, it can release heat at a higher temperature. Even when the outdoor temperature reaches 35ºC, there is still a temperature difference for heat to move from the system to the outdoor environment. This allows W2PC to support chiller-less cooling when the site conditions and cooling load are suitable.

 

• Reducing Site Infrastructure

 

W2PC is designed to reduce the infrastructure needed for high-density AI cooling. It does not require raised floors, separate chilled-water piping, or a chiller-based cooling system. Its modular design can also reduce the time and engineering work needed for deployment.

 

Planning a new AI facility or cooling upgrade? CreAlien can help evaluate whether W2PC fits your site conditions and cooling load.