An RDHx mounts on the back of a server rack and cools exhaust air directly — up to 160 kW per rack, no raised floor or room AC changes needed. This makes it easy to retrofit into existing data centers without major infrastructure changes. RDHx units are especially suited to high-density racks where traditional room-based cooling can’t keep up.

Active RDHx units use built-in fans to actively cool exhaust air, reacting fast to load changes. Passive units have no fans of their own and rely on the server’s own airflow to push air through the cooling coil. This makes active units better suited to variable, high-density workloads like AI and HPC, where cooling demand can spike quickly. NGC’s Active Flow is an active RDHx, built specifically for these environments.

NGC’s Active Flow RDHx cuts cooling energy use by up to 90% vs. traditional room-based air cooling. This is because it removes heat directly at the rack instead of cooling an entire room to a safe temperature. Lower energy use also means lower operating costs and a smaller carbon footprint for the facility. It’s one of the main reasons data centers are moving toward rack-level liquid cooling for AI and HPC workloads.