Preparing for the 800-volt Revolution

The 800-Volt Data Center Is Coming. Are Our Cooling Strategies Ready?

AI is accelerating a fundamental shift in data center design, pushing beyond incremental increases in rack density. As next-generation AI systems push toward 500 kW to 600 kW per rack, the industry must rethink not just how we cool infrastructure, but how we power it.

At the center of this transformation is the emerging move to 800-volt DC power architecture. This change promises efficiency gains, reduced copper usage, and improved scalability. While much of the conversation has focused on power delivery, a critical question remains:

What happens when high voltage meets liquid cooling?

The Rise of the 600 kW Rack

For years, rack densities hovered between 3 kW and 15 kW. Today, that paradigm is shifting rapidly. Modern AI systems, driven by increasingly power-hungry GPUs, are already reaching well beyond 100 kW per rack, with projections pushing toward 600 kW and beyond.

This shift is not just about performance — it’s about scale. Training advanced AI models requires tightly coupled, high-density compute environments that can deliver unprecedented processing power in a compact footprint.

To support this, traditional 48V architectures begin to break down. Above roughly 400 kW per rack, the amount of copper required becomes economically and physically impractical.

The solution? Increase the voltage.

Why 800V DC Is Gaining Momentum

Transitioning to 800V DC enables more efficient power distribution by reducing current, minimizing resistive losses, and significantly lowering copper requirements. It also simplifies system architecture and improves overall reliability.

In short, higher voltage makes ultra-high-density racks feasible. But it also introduces a new variable into the equation: risk.

As voltage increases, so does fault energy potential. Electrical arcs become more powerful. Insulation becomes more critical. And perhaps most importantly, the interaction between electricity and cooling fluids becomes far more consequential.

Cooling in a High-Voltage Environment: A Hidden Challenge

Liquid cooling, particularly single-phase direct-to-chip (DLC), has already proven itself as a viable solution for managing high heat loads. But most of these systems rely on water-based fluids or liquids with conductive properties.

At lower voltages, this has been manageable.

But we can’t cool a 800V 600 kW rack the same way we cooled 135 kW.

When conductive or semi-conductive fluids are exposed to high voltage, they can undergo electrolysis, a process that splits water molecules into hydrogen and oxygen gases.

Individually, these gases are manageable. Together, they create a well-known risk: a combustible mixture.

In a high-density, high-energy environment, the formation of hydrogen and oxygen introduces the potential for pressure buildup, system instability, and in extreme cases, explosion risk.

This is a direct consequence of combining high voltage (800V DC) + conductive fluids + confined environments.

Why Electrical Isolation Now Matters More Than Ever

As data centers evolve, cooling systems can no longer be evaluated on thermal performance alone. They must also be assessed through the lens of electrical behavior.

At 800V, even minor leakage currents or unintended conductive paths can have amplified consequences. This makes electrical insulation at the chip and system level a critical design requirement. It’s not just a nice-to-have.

In other words, cooling systems must now do two jobs:

Remove heat efficiently
Prevent electrical interaction with high-voltage components

This dual requirement represents a significant shift in how cooling strategies are evaluated and deployed.

Rethinking Cooling: The Role of Dielectric and Two-Phase Approaches

To address these challenges, the industry is increasingly exploring dielectric cooling technologies, particularly two-phase systems that use refrigerants instead of water-based fluids.

Unlike traditional liquids, dielectric fluids are electrically insulating, meaning they do not conduct electricity and are not susceptible to electrolysis.

This has several important implications:

No hydrogen/oxygen gas generation
Reduced risk of electrical faults interacting with coolant
Improved safety in high-voltage environments
Are current cooling strategies compatible with high-voltage architectures?
How should risk be evaluated in next-generation deployments?
What role should electrical insulation play in cooling system design?
How quickly can the industry adapt to these new requirements?
AI is driving unprecedented power density
800V DC is emerging as a necessary evolution
Cooling strategies must evolve alongside it

Additionally, two-phase cooling leverages phase change (liquid to vapor) to remove heat, allowing for highly efficient thermal transfer with minimal temperature rise, even as power levels increase.

From a design perspective, this creates a compelling alignment: A cooling medium that is both thermally effective and electrically inert.

A Shift in Design Thinking

The move to 800V DC is a transformation. And like any transformation, it requires rethinking long-standing assumptions. For decades, cooling and power have been treated as largely separate domains. But at ultra-high densities and voltages, they become deeply interconnected. Design decisions in one domain directly impact the other.

This raises important questions for operators, engineers, and designers:

We know the industry is not fully prepared. The challenges span across electrical codes, component readiness, and supply chain maturity.

Preparing for the 800V Future

The data center of tomorrow will not only be hotter and denser — it will also operate at significantly higher voltages.

The trajectory is clear:

That reality demands a new approach to cooling. It must account for both thermal performance and electrical safety.

Because in the 800V era, it’s no longer just about removing heat. It’s about managing energy safely, holistically, and intelligently

Watch the Full Webinar

To explore this topic in more detail, including technical insights, system considerations, and industry implications, watch the full on-demand webinar featuring Dave Meadows, Director of Technology at STULZ.

Watch the Webinar On-Demand: STULZ Webinar: Preparing for the 800-volt DC Revolution