A server includes a chassis including a first sidewall, a second sidewall, a rear wall, a front wall, and a partition wall. A receiving space to receive a power module is bound by the front wall, the partition wall, and front portions of the first and second sidewalls. A number of through holes is defined in each of the rear wall, the front wall, and the front portions of the first and second sidewalls. An outlet and an inlet of the power module face the first sidewall and the second sidewall, respectively. A part of the partition wall between the inlet and the first sidewall does not define through holes. Another part of the partition wall defines a number of through holes. A number of data storage devices is located between the partition wall and the rear wall. A number of fans is located outside the rear wall.