Layer 1 · How the heat leaves
Rear-door heat exchangers
Operators pushing an existing air-cooled hall further without replumbing it.
The shape of it
- Capital cost
- Moderate; retrofits into existing halls
- Maturity
- proven
- Density supported
- ~30-50 kW per rack
- PUE
- 1.2-1.4
Verified 2026-09-06.
The catch
A bridge, not a destination. It buys you one density step and then you are having the direct-to-chip conversation anyway.
What it actually decides
The best retrofit-in-place option. Buys time, not headroom.
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
- Direct-to-chip liquid cooling — 50-200+ kW per rack
- Single-phase immersion — 100+ kW per rack equivalent
- Two-phase immersion — Highest available
- Free and evaporative cooling — Depends on the paired system