Liquid vs. Air: Managing H100 Thermals

The NVIDIA H100 SXM5 has a TDP of 700W. A standard 8-GPU chassis pulls over 6kW continuously. In a standard 42U rack, air cooling is no longer a viable engineering strategy. It is time to talk about plumbing.

The Physics of Air Failure

Air has a low specific heat capacity. To cool a dense rack of H100s (approx 40kW - 60kW per rack), you need hurricane-force airflow. This creates two problems:

• Acoustic Damage: Fans spinning at 15,000 RPM create vibrations that can actually degrade hard drive performance (throughput latency) in nearby storage arrays.
• Power Parasitism: In an air-cooled high-density data center, nearly 30% of the total energy bill is spent just moving air (fans + HVAC).

Direct-to-Chip (DLC) Implementation

At Iteronix, our standard deployment for H100 clusters is Single-Phase Direct-to-Chip Liquid Cooling. We replace standard heatsinks with cold plates.

The ROI of Liquid

While the CapEx of a liquid loop (CDU + Manifolds) is roughly 15% higher than air, the OpEx reduction is drastic. By removing the need for CRAC (Computer Room Air Conditioning) units to fight the GPUs, we see a 40% reduction in monthly electricity costs for the same compute output.