- Pin connectors are essential for connecting motherboards to power supplies and delivering energy to various components.
- The ATX standard has gone through multiple revisions, with each version introducing changes and improvements.
- The ATX12V 2.x standard shifted towards using a 12V connector for powering all PC parts, making the 3.3V and 5V connectors impractical.
- Other types of connectors include the EPS connector for powering the CPU, PCIe connector for graphics cards, SATA connector for mass storage devices, and the obsolete 4-pin floppy connector.
Pin connectors are how our motherboards interface with our power supplies. They send energy from the PSU to the various components installed on our mobos. There are several types of pin adapters that you’ll see. Let’s explore them in detail and look at their history and usage.
ATX Pin Connectors
One of your motherboard’s most common and crucial pin connectors is the Advanced Technology Extended (ATX). Created by Intel, it’s a continuation of the original AT standard. There are many variations of ATX adapters, such as microATX, FlexATX, nano-ITX, and mini-ITX for smaller motherboards and EATX for dual socket motherboards. Let’s examine the different form factors.
Released in 1995, the original ATX standard started an empire. It had three kinds of pin adapters. A 4-pin “Molex connector” was brought to the standard from the original AT standard documentation. Additionally, the standard details the 4-pin “Berg connector,” also from the original.
Finally, there’s the Molex Mini-Fit Jr., a 20-pin connector, which was new. There was also an additional 6-pin AUX plug. The standard used 5V and 3.3V rails for most electrical components (CPU, RAM, ISA, PCI, AGP, etc.) However, CPU fans and peripheral motors (CD-ROM, hard drives, etc.) used the 12V power line.
The standard ATX 20-pin connector didn’t suffice when powering the Pentium 4 processors, designed in 1999/2000. Thus, a new power-line adapter was necessary to use the upgraded chipset. So, the ATX standard was revised into the ATX 12V 1.x. Athlon 64 and AMD Athlon XP also adopted the ATX 12V 1.x standard for their systems. However, earlier Athlon MP and XP systems may have a different 4-pin plug from the new ATX standard.
The revisions in the ATX 12V 1.0 standard are as follows:
- They expanded the power of the 12V rail
- An additional Mini-Fit Jr. 4-pin connector was included, providing 12V power to the CPU
- It was given a minimum of 68% efficiency under a full load
Officially named the +12V Power Connector, the ATX 12V 1.0 standard was necessary to run the Pentium 4 processor line. Thus, it is sometimes referred to as the P4 Connector. This CPU line required 12V power, up from the previous 5V needed to run its predecessors. Later processors typically run at much lower power draws of around 1V.
Providing energy at such a low rate is physically infeasible. Thus, the Pentium 4 established the process of supplying power using a DC-to-DC converter placed on the motherboard alongside the processor — a 4-pin 12V connector powered this device.
This revision to the ATX 12V 1.0 standard came in 2000 and slightly increased the power of the 3.3V rail.
Ultimately, a minor change: 1.2 made the 5V connector optional since only ISA expansion cards chiefly utilized this adapter. However, by the point of this change, the ISA bus had fallen out of favor and was no longer included in most consumer computers. Thus, the power line was deemed obsolete.
This new standard introduced several changes. While these revisions were ultimately minor, the breadth of additional features was large enough to warrant a whole new version. The differences were as follows:
- It slightly expanded the thermal design of the 12V power line again
- It increased the minimal efficiency from 68% to 70% and detailed additional minimal PSU efficiencies of 50% for light loads and 60% for typical loads
- The new standard detailed acoustic levels
- They introduced the Serial ATA connector (specified as optional in this standard)
- Information for the 5V rail was removed (however, notably, the rail was not prohibited)
This revision of the ATX 12V standard brought significant changes in the system’s power distribution. Analysis of the power needs of computer components at the time yielded results indicating that it would be more cost-efficient to power all PC parts using a 12V connector rather than splitting certain parts into the 3.3V and 5V ones.
To begin with, PCIe cards and post-Pentium 4 CPUs were drawing most of their energy from the 12V rails. So, including the 3.3 and 5V rails was deemed impractical.
Moving from the 2.x to 2.0 ATX12V standards, we saw some major changes to the power distribution, spurred mainly by the new demands of the PCIe standard. The updates to the documentation include, but are not limited to:
- The primary power support is now the 12V rails
- There are two independent 12V rails with separate overcurrent protection
- The power supplied by the 3.3V and 5V rails was significantly reduced
- The ATX motherboard plug was expanded from 20 pins to 24 pins
- The AUX plug was taken out because the additional 3.3V and 5V pins it provided were included in the 24-pin adapter
- Power supplies are now required to have Serial ATA cables
- Minimum efficiency now increased to 60% under a light load, 70% under a typical load, and 70% under a full load
This minor revision removed a passing reference to the 5V connector in the documentation and introduced some other minor adjustments.
Released in March 2005, this version increased the power supplied to all rails and efficiency requirements. Now, 65% efficiency is necessary under light loads, 72% under typical loads, and 70% under loads. However, the recommended minimum efficiency in documentation is 75% on a light load, 80% on a typical load, and 77% on a full load.
Also introduced in March 2005, this included documentation for high current series wire terminals on the 24-pin motherboard plugs, as well as the 4-pin CPU connectors.
This version came in March 2007. It increased the recommended efficiency of power supplies to 80% on a light load and a minimum of 70% at all times. These new recommendations aligned the standard with the latest Energy Star 4.0 mandates.
Intel also lowered the requirement for the 12V rails, allowing the plug to be compatible with CPUs with a very low power draw. Finally, this version removed the 240V overcurrent limit, which allowed 12V lines to send more than 20 A per rail.
This revision in February 2008 provided a maximum ripple/noise specification of 400 millivolts to the POWER_ON and POWER_OK signals. It also mandated that the DC power must maintain power for longer than one millisecond after the POWER_OK signal ends.
This version also detailed country-specific input line harmonics and electromagnetic compatibility requirements. It also added a section about Climate Savers and updated power supply configuration recommendations and cross-regulatory graphs.
This isn’t an actual standard. It’s the unofficial moniker the community gave to the documentation published in May 2020.
Released in August 2021, Intel mentions these specifications in the revised documentation for ATX 1.3, which explicitly names them ATX12V 2.4.
Intel published these standards in September 2021 and brought in support for Alternative Sleep Mode, implemented by Windows 10 as Modern Standby.
Released in December 2021, this specification represents another minor change to the ATX12V standard documentation. It makes additional recommendations on the efficiency of components affixed to the motherboard. Additionally, it includes references to the Energy Star Computers Specification Version 8.0.
Published in February 2022, these guidelines for the ATX12V 3.0 standard include information regarding the 16-Pin 12vHPWR connector, a new connector designed to power graphics cards with up to 600 watts of energy.
Additionally, the new specifications include data on negotiating power draw with the PSU to ensure that no component draws more energy than the power supply can deliver. It also has stricter regulations regarding handling power spikes, two times the rated output for 100 microseconds.
The EPS, or Entry-Level Power Supply Specification, cable is the one that will drive power to the CPU. In modern computers, it’s an 8-pin cable. However, older computers may use a 4+4-pin cable.
PCI Express, or PCIe, cards that require additional power from the power supply may use a 6+2-pin connector. The most common component to use this plug is a PC’s graphics processing unit (GPU), which typically draws enough power to require its own direct connection to the PSU.
Serial ATA, or SATA, connectors transfer power between the PSU and mass storage devices, like hard drives, solid-state drives, and disk drives. Intel first mandated their inclusion on PSUs in the ATX12V 2.0 standard documentation.
4-Pin Floppy Connector
While this adapter has been obsolete for years, you may still find it connected to your power supply for some unfathomable reason. The chances of finding one on your motherboard are low. So, don’t go buying a floppy drive just yet.
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