NVIDIA GB200 NVL72 cooling requirements

The GB200 NVL72 rack is 132 kW of compute in a single tile. This is what our crews specify, install and commission for it — no marketing filler.

Thermal load per rack

• 72 × Blackwell GPUs + 36 × Grace CPUs, direct-to-chip cooled.
• Total design load: 120–132 kW/rack.
• DLC captures ~85%; residual ~20 kW to air (NVSwitch trays, PSUs, ToR).

Coolant and loop spec

• Coolant: demineralised water + OEM inhibitor. PG25 only where freeze is a real risk.
• Supply temp: 32–40 °C at the rack inlet.
• ΔT: 10 K design, 12 K trip.
• Flow: ~3.1 L/s per rack at 10 K.
• Filtration: 50 μm at CDU inlet, 5 μm inline.

CDU and manifold

Plan one L2L CDU per 6–8 racks (approximately 800–1,000 kW rated). Manifold material: stainless with EPDM-sealed dripless quick-disconnects. Every rack drop gets an isolation valve, flow meter and leak rope.

Commissioning gates

1. Hydrostatic test at 1.5× MAWP for 4 h, zero pressure drop.
2. Chemical passivation and 24 h air-separator run.
3. Loop de-aeration verified by clear-sight glass.
4. Full-load ΔT sweep at 25/50/75/100%.
5. Simulated pump trip, CDU failover under load.
6. Leak-rope end-to-end test with distilled water on tray.

Field gotchas

• Under-sized expansion tanks pop relief valves during first warm-up.
• Mixed-metal manifolds without dielectric unions corrode within 12 months.
• QD misalignment on hot-swap causes seep leaks — torque the rack rails first.
• Facility water TDS above 150 ppm fouls the CDU heat exchanger in a season.