Accelsius Two-Phase Cooling Keeps NVIDIA B200 GPUs 9°C Cooler Than Single-Phase

Accelsius, a company specializing in two-phase, direct-to-chip liquid cooling for AI and high-performance computing, has released results from independent third-party benchmark testing showing that its two-phase cooling technology outperforms conventional single-phase cooling as facility water temperatures rise, a trend NVIDIA has been pushing the industry toward as a way to enable more "free cooling" using ambient conditions rather than energy-intensive chillers. The testing found that Accelsius NeuCool system, running with facility water at 54°C, could match the thermal performance that single-phase cooling achieves at NVIDIA's newer 45°C standard, meaning operators could run meaningfully warmer water without sacrificing cooling performance.

This matters because warmer facility water directly translates into energy savings, with each 1°C increase in allowable water temperature yielding roughly 4 percent in annual energy savings, and it also opens the door to relying on outside air or water sources to cool the system instead of mechanical refrigeration, an approach often called free cooling. By pushing usable facility water temperatures past 50°C, NeuCool makes free cooling viable in most parts of the world for much of the year, which is increasingly important as AI infrastructure gets built out in hotter regions.

The benchmarking itself was ca...