SMPS full form is Switching Mode Power Supply. It is the main power supply to power each and every component of the computer or it converts the main power supply 230volts to 12volts, 5volts, 3volts and distributes to all components of the computer.
Three Types of SMPSs are
1. AT SMPS:
AT stands for Advanced Technology. These are all old SMPSs. They had a 12pin power connector, this is called as AT power connector. They were used in Pentium-I, Pentium-MMX, Pentium-II, and Pentium-III CPUs.
ATX stands for Advanced Technology extended. They had a 20pin Power connector, which is called as ATX power connector. They were used in Pentium-III, Pentium-IV, and AMD CPUs.
BTX stands for Balanced Technology extended. They have a 24pin Power connector, which is also called as ATX power connector. It has 15pin SATA power connectors. They are used in Dual-core, core2duo, Quad-core, i3, i5, i7, and latest AMD CPUs.