An electrical assembly that allows a plurality of electronic assemblies to be cooled by a number of fans. The assembly includes a housing which has a plenum chamber that is located between a rack chamber and a fan chamber. The rack chamber is separated from the plenum chamber by a backbone wall. The fan chamber is separated from the plenum chamber by a fan wall that is perpendicular to the backbone wall. The rack chamber contains a plurality of electronic assemblies such as hard disk drives. The fan chamber contains a plurality of individual fans. The fans induce an air flow from the rack chamber to the fan chamber through the plenum chamber. The plenum chamber provides a uniform pressure that induces an equal flow rate across each disk drive in the rack chamber. The fans are controlled by a control circuit which can detect the failure of one fan and increase the speed of the remaining fans to maintain the plenum chamber pressure. The constant plenum chamber pressure insures an equal flowrate across each disk drive even when one of the fans fails.