What is an ATX Style Connector?

ATX Design in 1995, Intel created ATX (Advanced Technology eXtended), a motherboard and power supply configuration standard to create on previous factor standards like the AT architecture. It was the first significant modification in the Design of a desktop computer shell, motherboard, and power supply in many years. As a result, it helped in improved part standardization and interchangeability. The standard specifies the dimensions, mounting positions, I/O panel, and power and connection intersection between a computer case, a motherboard, and a power supply.

The earlier P8 and P9 AT-style connectors have been replaced by an ATX-style connection. It is one of the computer's largest connections. It connects an ATX-style motherboard to a power supply. As seen in the illustration, the 20-pin cable is a multi-colour cable that may be identified as P1.

The ATX cable connector in the image includes a little clip on the top that clicks into place and holds the cable in place. It connects only in one direction, so it is also keyed.

By keeping the four extra pins unconnected, a power supply with a 24-pin connection can be utilized on a motherboard with a 20-pin connector. If your motherboard has a 24-pin connector, you must connect all 24-pins. You will need to purchase a new power supply if your current one does not include a 24-pin connector.

The ATX form factor is the most prevalent motherboard configuration. Other smaller board standards (such as microATX, FlexATX, nano-ITX, and mini-ITX) preserve the basic back layout but reduce the board's size and the number of expansion slots. The dimensions of a full-size ATX board are 12 × 9.6 in (305 × 244 mm), allowing microATX boards to fit into many ATX chassis.

A brief history of ATX Style Connector

The ATX specifications were first issued by Intel in 1995, and they have been revised multiple times since then. Version 2.2 of the ATX motherboard specification is the most recent. 2.53 was announced in June 2020 as the most recent ATX 12V power supply unit specification. The EATX (Extended ATX) motherboard is a larger variant of the ATX motherboard, with dimensions of 12×13 in (305 × 330 mm). At the same time, certain motherboards with multiple CPU sockets have been released.

The BTX (Balanced Technology Extended) standard was announced by Intel in 2004 as a substitute for ATX. Intel chose to cease developing BTX in 2006, despite the fact that several manufacturers had accepted the new standard. The ATX architecture is still the de facto standard for personal computers in 2022.

Connectors

On the back of the computer chassis, the AT standard was drastically altered. Originally, AT cases just included a keyboard connector and expansion slots for back plates for add-on cards. Any additional onboard interfaces (such as serial and parallel ports) must be linked to case-provided connectors or brackets fitted in unused expansion slot positions using flying leads.

ATX permitted any motherboard manufacturer to place these ports in a rectangular space on the rear of the system with their own order, while most manufacturers followed a few broad patterns based on what ports the motherboard offered. A snap-out panel, also known as an I/O plate or I/O shield, is fitted in the casing in one of the most common designs.

I/O plates can be swapped if necessary to suit a motherboard that is being installed; I/O plates are typically offered with motherboards that are not tailored for a specific machine. The computer will function normally without the plate, but there will be open spaces in the casing that may weaken the EMI/RFI screening and enable dirt and other foreign objects to enter. Panels were created to allow an AT motherboard to be installed in an ATX chassis. An integrated I/O plate is available on some ATX motherboards.

The ATX standard also made PS/2-style mini-DIN keyboard and mouse ports commonplace. The keyboard on AT computers had a 5-pin DIN connection, and serial port mice were commonly utilized (although PS/2 mouse interfaces were also found on select systems). PS/2-style keyboard and mouse ports are being phased out on many contemporary motherboards in favor of the more modern Universal Serial Bus. 25-pin parallel connections and 9-pin RS-232 serial ports are two further outdated connectors that are steadily being phased out of current ATX motherboards Ethernet, FireWire, eSATA, analogue and S/PDIF audio, video (analogue D-sub, DVI, HDMI, or DisplayPort), extra USB ports, and Wi-Fi is all available onboard.

The ATX specification has a key fault in that it was last revised at a time when power supplies were frequently mounted at the top of computer cases rather than the bottom. As a result, a number of common port locations have become problematic, notably the 4/8 pin CPU power port, which is often located along the board's top edge to allow for a top-mounted power supply. This makes cables from bottom-mounted power sources difficult to reach and sometimes demands a unique hole in the backplane for the cable to come in from behind and curve around the board, complicating insertion and wire management. Many power supply cables barely reach or fail to reach due to their configuration or are too hard to bend, necessitating the installation of extensions.

Power Supply

The power supply must generate three major outputs: +3.3 V, +5 V, and +12 V. According to the ATX specification, Low-power 12 V and +5 VSB (standby) supplies are also required. The 12 V supply provides the negative supply voltage for RS-232 ports, and one pin on common PCI slots is used to give a reference voltage for some sound card types. When a PC is turned off, the 5 VSB supply generates trickle power for ATX's soft-power function, as well as powering the real-time clock to conserve the CMOS battery's charge.

One 20-pin connection was used to power the motherboard at first. An ATX power supply has a variety of peripheral power connections as well as (in current systems) two motherboard connectors: an auxiliary 8-pin (or 4+4-pin) connector for additional CPU power and a primary 24-pin power supply connector, which is an expansion of the original 20-pin version. At the motherboard, MOLEX 39-29-9202 is a 20-pin MOLEX connector. A 20-pin MOLEX 39-01-2200 is found on the cable. On the connection, the pin pitch is 4.2 mm (one-sixth of an inch).

Physical Characteristic

ATX power supplies have the identified width and height as the preceding LPX (Low Profile eXtension) form factor (which are often incorrectly referred to as "AT" power supplies due to their widespread use in later AT and Baby AT systems, despite the fact that the actual AT and Baby AT power supply form factors were physically larger), as well as a four-screw mounting layout. With depths of 160, 180, 200, and 230 mm, the 140 mm depth is constantly modified.