A modular computer system (e.g., a server blade system) includes a carrier (e.g., a rack mountable shelf) carrying a plurality of removably mountable information processing modules (e.g., server blades). Each information processing module can include a processor operable to provide information processing functions and a service controller operable to provide monitoring and system management functions. The carrier and the information processing modules can be interconnected by separate information and service management paths so that system management signals can be communicated independently of information signals. A combined switch and service processor module can be provided in the carrier. The switch and the service processor can be interconnected via a communications link for controlled information passage between a management network and the information processing modules via an information path.