A server includes a casing, a storage module and a motherboard. The casing includes a chassis and two side plates. The two side plates stand on the chassis. The storage module is disposed on the chassis. The motherboard includes a circuit board, at least one central processing unit, a first amplifier, a second amplifier, a riser card and a third amplifier. The circuit board is disposed on the chassis. The at least one central processing unit, the first amplifier and the second amplifier are disposed on the circuit board. The riser card is disposed on the second amplifier. The third amplifier is disposed on the riser card.