SMPS stands for switch mode power supply. It provides direct current to mother board and disks drive through three types of connecters. Two six wires connectors supply power to the mother board. They plug into the board side by side with the black wires of each connector next to each other.
Each SMPS power supply has several four wire connectors. The smaller four wire connector power floppy disk drive and the large ones are used for hard disk drive and other peripherals.