A sever including a chassis, at least one first tray, at least one second tray, a power supply module, multiple input/output interface circuit boards, and multiple mother boards is provided. The first and second trays are slidably disposed in the chassis, and the first and second trays can be drawn out of the chassis in opposite directions. The power supply module is disposed on a bottom plate of the chassis. The input/output interface circuit boards are disposed on the first tray, respectively. The power supply module is located between two input/output interface circuit boards. Each input/output interface circuit board has multiple input/output interfaces. The mother boards are disposed on the second trays, respectively. The input/output interface circuit boards and the power supply module are correspondingly electrically connected to the mother boards.