Settings are provided by a chassis management controller to an expansion card in a multi-slot server chassis. The chassis management controller in a multi-slot server chassis provides an operating parameter to a server management controller in a server, and the server management controller writes the operating parameter to a port expander of an expansion card installed on the server. The operating parameter is written to the port expander prior to expansion card power up, and the expansion card uses the operating parameter after power up to derive one or more SERDES value. The SERDES value is used to program an ASIC chip comprising a SERDES converter on the expansion card. In one example, the operating parameter is determined by the capabilities of a chassis midplane at the slot where the compute node is installed.