A cable backplane system includes a plurality of cable connectors interconnected by cables, each cable connector having a header holding signal contacts at a mating end of the header configured for mating with a card connector. A cable tray having side walls surrounds a cavity defining a raceway for the cables. The cable tray has a front edge and holds header frames between the side walls. The header frames hold headers of corresponding cable connectors. An organizer plate is coupled to the cable tray at the front edge. The organizer plate has a plurality of connector channels receiving mating ends of corresponding headers. The connector channels hold the headers in position relative to one another.