Connectors

Last Updated on Sun, 19 Feb 2023 | Operating Systems

Most connectors today are keyed connectors. Keyed connectors are designed to be inserted in only one direction. Each part of the connector has a colored wire with a different voltage running through it, as described in Table 1-1.

Note

Different power supply form factors provide different power output connections, depending on system requirements. AT form factors have been slowly phased out by ATX form factor power supplies because of the different case sizes and advanced features. ATXv12 was created to add power support for the motherboard by adding another four-pin power connector.

Table 1-1 Power Color Codes

Voltage

Wire Color

Use

AT Power Supply Form

ATX Power ATXv12 Power Supply Form Supply Form

+12V

Yellow

Disk drive motors,

✓

✓ ✓

fans, cooling

devices, and

system bus slots

Readers' Questions

amanuel
Which power supply connector is the main motherboard power connector on most motherboards today?

2 months ago
- Reply

The main motherboard power connector on most motherboards today is the 24-Pin ATX Power Connector.

James
What are molex connectors used for?

2 months ago
- Reply

Molex connectors are used to connect power and data cables to devices within a computer or other electronic system. They are often used to connect a power source to components such as disk drives, fans, and other internal devices.

Belba
What is a keyed connector?

2 months ago
- Reply

A keyed connector is a type of electrical connector that is designed to be used with a specific mating connector, and the two connectors are not compatible with any other type. Keyed connectors are used for security, to prevent unauthorized connections, and to prevent incorrect connection.

Table 1-1 Power Color Codes continued

Voltage	Wire Color	Use	AT Power Supply Form	ATX Power ATXv12 Power Supply Form Supply Form
-12V	Blue	Some types of serial port circuits and early programmable read-only memory (PROM)	✓	✓ ✓
+3.3V	Orange	Most newer CPUs, some types of system memory, and AGP video cards		✓ ✓
+5V	Red	Motherboard, Baby AT and earlier CPUs, and many motherboard components	✓	✓ ✓
-5V	White	ISA bus cards and early PROMS	✓	✓ ✓
0V	Black	Ground: Used to complete circuits with the other voltages	✓	✓ ✓

Different connectors are used to connect specific components and various locations on the motherboard:

■ A Molex connector is a keyed connector used to connect to an optical drive or hard drive.

■ A Berg connector is a keyed connector used to connect to a floppy drive. A Berg connector is smaller than a Molex connector.

■ A 20-pin or 24-pin slotted connector is used to connect to the motherboard. The 24-pin slotted connector has two rows of 12 pins each, and the 20-pin slotted connector has two rows of 10 pins each.

A four-pin-to-eight-pin auxiliary power connector has two rows of two to four pins and supplies power to all areas of the motherboard. The four-pin-to-eight-pin auxiliary power connector is the same shape as the main power connector, but smaller.

■ Older standard power supplies used two connectors called P8 and P9 to connect to the motherboard. P8 and P9 were unkeyed connectors. They could be installed backwards, potentially damaging the motherboard or power supply. The installation required that the connectors were lined up with the black wires together in the middle.

Note

If you have a difficult time inserting a connector, try a different way, or check to make sure that no bent pins or foreign objects are in the way. Remember, if it seems difficult to plug in any cable or other part, something is wrong. Cables, connectors, and components are designed to fit together snugly. Never force any connector or component. Connectors that are plugged in incorrectly will damage the plug and the connector. Take your time, and make sure that you are handling the hardware correctly.

Continue reading here: Electricity and Ohms Law

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