A direct-interface liquid-cooled (DL) Rack Information Handling System (RIHS) includes liquid cooled (LC) nodes each comprising a chassis received in a respective chassis-receiving bay of a rack and containing heat-generating functional components. Each LC node is configured with a system of conduits to receive direct injection of cooling liquid to regulate the ambient temperature of the node and provide cooling to the functional components inside the node by removing heat generated by the heat-generating functional components. A cooling subsystem has a liquid rail formed by more than one node-to-node, Modular Liquid Distribution (MLD) conduits, each including first and second terminal connections attached on opposite ends of a central conduit that can be rack-unit dimensioned. The MLD conduits seal to and enable fluid transfer between a port of a selected LC node and a port of an adjacent LC node.