A computer includes a number of hard disk drives (HDDs), a number of Serial Advanced Technology Attachment (SATA) connectors correspondingly connected to the HDDs, and a number of jumpers. Each SATA connector includes a power supply pin, a spin-up pin, a ground pin, and a pin base with first to third pins. The first to the third pins are respectively connected to the power supply pin, the spin-up pin, and the ground pin. The second pin of each SATA connector is connected to either the first pin or the third pin by a corresponding jumper, thereby the corresponding HDD starts up with the computer or starts up at a preset time after the computer has started up.