Voltage Distribution on a computer system

The power supply unit of a computer system unit can be defined as the unit which energizes the circuit of the system.

There are basically two types of power supply unit in a computer system.

AT [advanced technology]

 This refers to the computer supply type which makes use of two pin connector [P8 and P9]. The two pins are attached directly to the motherboard to supply a  d.c to the motherboard. The AT power supply makes use of manual switching circuit.

When 220/240v a.c is supplied via the wall socket into the computer system, the power supply unit of the computer system step-down and converts the voltage to 12v d.c.

NOTE: when installing the connectors on the motherboard, the two black wires [from the P8 and P9],must face each other.

Direct current [D.C]: This refers to current that flows in one direction

Alternating current [A.C]: this refers to current that flow in a sinusoidal way

ATX Power Supply Pinout

ATX [advanced technology extension]: this is the power supply unit type which is found on most modern systems. It supplies 12v d.c into the motherboard which is then distributed evenly   as outlined below. The two connectors are joined together unlike that of AT in which the two connectors are separated.

Below is a table displaying the voltage distribution on a Typical Computer System.

Study carefully