Legacy air handles under ~30‑50 kW per rack – the vast installed base. I map onto rack‑density bands that coexist: hybrid air‑liquid (rear‑door exchangers plus coolant overlays) covers the 50‑100 kW mainstream, favored because it retrofits existing buildings. Direct‑to‑chip liquid owns the 100‑240 kW AI band, while immersion stays a hyperscaler experiment at 240 kW‑plus, greenfield‑only. Operators’ surveys put retrofit ease at 46% as the top viability criterion, so brownfield moves through hybrid stages while new AI campuses jump straight to direct‑to‑chip.
← stream@cooling-transition needs