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Liquid Cooling vs. Air Cooling: Choosing the Right Solution for High-Density GPU Facilities

Liquid Cooling vs. Air Cooling: Choosing the Right Solution for High-Density GPU Facilities

Summary

As AI chip power consumption continues to rise (NVIDIA H100 reaches 700W, B200 exceeds 1000W), traditional air cooling solutions are approaching their limits. This article provides an in-depth comparison of liquid cooling and air cooling applications in high-density GPU facilities, helping enterprises make the right cooling decisions.

I. Current Cooling Challenges

1.1 Surging Power Density

  • Traditional Racks: 5-10 kW/rack
  • AI Racks: 40-100 kW/rack (e.g., one rack with 8 HGX H100 servers can exceed 80kW)

1.2 Air Cooling Limits

  • Physical Limitations: Low air heat capacity, requires extremely high airflow to remove high heat
  • Noise Issues: Extremely high fan speeds, facility noise can exceed 100dB
  • Energy Efficiency Bottleneck: PUE (Power Usage Effectiveness) difficult to reduce below 1.4

II. Technical Solution Comparison

2.1 Traditional Air Cooling

Utilizes precision air conditioning (CRAC) and hot/cold aisle containment technology.

  • Advantages: Mature technology, low construction cost, simple maintenance
  • Disadvantages: Limited cooling capacity (<30kW per rack), high energy consumption
  • Applicable Scenarios: General servers, medium-low density inference nodes

2.2 Direct Liquid Cooling (DLC/D2C)

Coolant passes through cold plates directly contacting heat-generating components (GPU/CPU).

  • Advantages:
    • High cooling efficiency (can remove 70-80% of heat)
    • PUE can be reduced to 1.1-1.2
    • Supports extremely high density (>50kW/rack)
  • Disadvantages:
    • Requires dedicated pipelines and CDU (Coolant Distribution Unit)
    • Leakage risk (though modern technology has significantly reduced this)
  • Applicable Scenarios: High-performance computing (HPC), large-scale AI training clusters

2.3 Immersion Cooling

Entire servers immersed in non-conductive coolant.

  • Advantages:
    • Highest cooling efficiency (100% liquid cooling)
    • PUE can approach 1.05
    • No fans, extremely quiet
  • Disadvantages:
    • High equipment modification costs
    • Difficult maintenance (requires hoisting equipment to drain)
    • Extremely high floor load requirements
  • Applicable Scenarios: Extreme density scenarios, mining farms, specific supercomputing centers

III. Economic Analysis (Example: 1MW Facility)

| Item | Air Cooling | DLC Liquid Cooling | Difference Analysis | |------|-------------|-------------------|---------------------| | Initial Construction (CapEx) | Baseline | +30% | Higher liquid cooling equipment and pipeline costs | | Rack Count | 100 racks (10kW/rack) | 20 racks (50kW/rack) | Liquid cooling significantly saves space | | PUE | 1.5 | 1.2 | Liquid cooling more energy efficient | | Annual Electricity Cost (OpEx) | Baseline | -20% | Saves air conditioning electricity costs | | Total Cost of Ownership (TCO) | Baseline | Golden cross after 3 years | Long-term operations liquid cooling more cost-effective |

IV. HuiSuan Global Recommendations

For customers planning AI compute centers, we recommend a hybrid strategy:

  1. Core Training Zone:

    • Adopt DLC Direct Liquid Cooling
    • For H100/B200 and other high-power nodes
    • Pursue ultimate performance and density

  2. Inference & Management Zone:

    • Maintain High-Performance Air Cooling (with hot/cold aisle containment)
    • For L40S, CPU servers, network equipment
    • Balance cost and versatility

V. Conclusion

Liquid cooling is not the future, but the present. For AI clusters with single-rack power exceeding 30kW, liquid cooling is already a necessity, not an option. HuiSuan Global has extensive experience in liquid cooling facility design and transformation, and can help you smoothly transition to the liquid cooling era.

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