A cable backplane system includes a backplane having a plurality of openings therethrough and a plurality of mounting blocks. A cable rack is coupled to a rear of the backplane and includes a tray having a frame surrounding a raceway. Spacers are coupled to the tray that are secured to corresponding mounting blocks to position the spacers relative to the backplane. Cable connector assemblies are held by the tray. Each cable connector assembly has a plurality of cables extending between at least two cable connectors. The cables are routed in the raceway. Each cable connector assembly is positioned between and supported by corresponding spacers on opposite sides of the cable connector assemblies. The spacers allow limited movement of the cable connectors in at least two directions to allow alignment of the cable connectors within corresponding openings in the backplane.