A cable backplane system includes a backplane having board areas surrounding a connector opening with holes in the board areas along the connector opening. Stiffeners are coupled to corresponding board areas along a front of the backplane. The stiffeners have bores aligned with corresponding holes in the backplane. A cable rack is coupled to the rear of the backplane. The cable rack has a tray with a frame surrounding a raceway and spacers coupled to the tray that hold corresponding cable connectors. The spacers have guide pins extending therefrom that pass through the holes in the backplane into corresponding bores in the stiffeners to position the spacers relative to the stiffeners and the backplane. The cable connectors are received in the connector opening in the backplane and held in position relative to the backplane by the spacers and stiffeners.