Layer 1 · How the heat leaves
Free and evaporative cooling
Cold or dry climates, as an economiser on top of another method.
The shape of it
- Capital cost
- Moderate
- Maturity
- proven
- Density supported
- Depends on the paired system
- PUE
- Can push annualised PUE below 1.2 in the right climate
Verified 2026-09-06.
The catch
Evaporative cooling trades electricity for water, and water use (WUE) is becoming the more contested licence-to-operate issue in several regions.
What it actually decides
Nearly free efficiency where the climate allows. Increasingly constrained by water politics rather than engineering.
What this is powering
A GB200 NVL72 rack draws 120–132 kW and a GB300 pushes 135–200 kW, against a 2026 average rack of about 27 kW. The silicon decision and the power decision are the same decision, made eighteen months apart.
Layer 2 — Silicon · GB200 NVL72 · The 150 W inference option
Others in how the heat leaves
- Air cooling — Up to ~30 kW per rack
- Rear-door heat exchangers — ~30-50 kW per rack
- Direct-to-chip liquid cooling — 50-200+ kW per rack
- Single-phase immersion — 100+ kW per rack equivalent
- Two-phase immersion — Highest available