A server includes a chassis having a base and a cover, a switch mounted on the chassis, and a motherboard. The motherboard includes a control circuit and a power-on pin. The control circuit includes a switch unit, and the switch unit includes a first buffer, a switch chip and a jumper. When the cover is detached from the base, the switch outputs a first signal to the first buffer, and the first buffer outputs the first signal to the switch chip. The switch chip outputs the first signal to the power-on pin, and the server is powered off. When the base is covered by the cover, the switch outputs a third signal to the first buffer and the first buffer outputs the third signal to the switch chip. The switch chip outputs the third signal to the power-on pin, and the server is powered on.