A portable computer includes a chassis, a top panel, a motherboard, and a side cover. The chassis includes a bottom panel and a side panel. The bottom panel forms a pair of restricting tabs. The top panel covers the chassis. The top panel includes a plurality of resilient tabs. The motherboard is received in the chassis. The motherboard forms a plurality of sockets. The side cover is replaceably mounted between the chassis and the top panel, being held by the restricting tabs, the resilient tabs, and side panel. The side cover defines a plurality of slots for receiving the sockets of the motherboard.