Cooling

Rear-door heat exchangers and in-row coolers

A rear-door heat exchanger is a water coil on the back of a rack: server fans push exhaust through it and the air leaves near room temperature. It suits the air-cooled remainder of an AI hall, such as network and storage racks. In-row coolers are coarser and suit lower densities.

Source: https://www.supermicro.com/en/glossary/rdhx Checked 2026-09-18 unverified

Directly opened supermicro.com. It confirms the core mechanism (RDHx is a liquid-to-air heat exchanger on the rear of a rack that absorbs heat from server exhaust before it enters the room) but frames density differently from the body: Supermicro describes RDHx as suited to 'extremely high-density racks' rather than as cooling for the air-cooled remainder of a hall, and does not describe in-row coolers as 'coarser' or lower-density. Body wording flagged for human review against this source; confidence left unverified in the meantime.