An electronic device configured to be mounted in a housing of a cluster, the device comprising a rear body housing at least one mother board configured to be powered by the cluster, a front tray housing at least one electronic board having at least one socket, the front tray comprising at least one fastening member for mounting an expansion card having an edge connector and a fastening portion, the electronic board being connected to the mother board by at least one flexible cable, the front tray being mounted slidable relatively from the rear body between a close position and an open position in which the front tray is at least partially removed from the cluster housing while keeping the rear body into the cluster housing so that an expansion card can be mounted/unmounted from the electronic board without powering off the device.