Reliability is among the performance factors applied to multi computer systems consisting of active parallel hosts (clients) and a central server. For reliability evaluation and system performance, this study analyzed a multi computer system consisting of a three hosts (clients) connected to a central server. The system is configured as series-parallel system consisting of two subsystems A and B. Subsystem A consist of three clients working in parallel with each other while subsystem B consist of a central server. Both clients and server failure and repair time are to be exponentially distributed The system is analyzed using first order differential difference equations to derive the expressions for availability, mean time to failure, probability of busy period of repairman due partial or complete failure. The results are presented in tables and graphs. Reliability characteristics such as availability, MTTF, profit function as well as sensitivity analysis have been discussed. Some particular cases have also been derived and examined to see the practical effect of the model. The computed results are demonstrated by tables and graphs.