A disk drive assembly for a server system includes a drive bracket (30), a disk drive (10), and a backboard (50). The drive bracket includes a top wall (31) and two parallel sidewalls (34) perpendicular to the top wall. The disk drive is received in the drive bracket between the two sidewalls. The disk drive has a port (15) defined therein. The backboard is secured to the drive bracket and perpendicular to the top wall and the sidewalls thereof. The backboard includes a main body (51) and a connecting member (53) detachably mounted on the main body. The connecting member is connected to the port of the disk drive and facilitates communication between the disk drive and the server system.