An electronic device comprises a cooler comprises a plurality of first locking members, a backboard defining pluralities of first and second positioning holes, and a circuit board. The backboard is attached to the cooler through the first locking members engaged with the second positioning holes. A first mounting member and a second mounting member are adapted to receive the heat generating component. The first mounting member defines a plurality of locking holes. The first positioning holes are among the second positioning holes. The second mounting member receives the heat generating component, the circuit board is between the second mounting member and the backboard, the first mounting member is secured to the circuit board; when the first mounting member receives the heat generating component, the circuit board is between the first mounting member and the backboard, the first mounting member is secured to the backboard.