Pin connectors play a vital role in computing by transferring power from computer power supplies to motherboards, graphics cards, CPUs, storage devices, and more. As technology has progressed, different types of pin connectors have been developed and iterated on to improve power delivery.
In this comprehensive guide, we will explore the most common pin connectors you‘ll encounter inside a computer, including:
- ATX
- EPS
- PCI Express (PCIe)
- SATA
- Legacy 4-pin floppy
For each connector type, we’ll cover its purpose, a brief history, what components it connects to, and some example images. By the end, you’ll have an expert-level understanding of the inner workings of these crucial pieces of computer hardware.
A Brief History of Pin Connectors
The earliest electronic computers in the 1940s were powered by simple electrical connectors transferring energy directly from a power source to components. However, as computers advanced to utilize printed circuit boards (PCBs), standardized connectors were required to interface the boards with power supplies, peripherals, and other components.
Intel’s release of the AT (Advanced Technology) standard in the mid-1990s introduced the first widely adopted pin connector interface. AT laid the foundation for the ATX standard which followed shortly after, bringing several improvements.
Over time, increasing computing performance demands necessitated revisions to ATX to provide devices more power. This led to the creation of auxiliary connectors like EPS and PCIe designed specifically to power CPUs and graphics cards. Storage devices also began using dedicated SATA connectors.
Let’s explore these major pin connector standards in more detail.
ATX Connectors
The ATX (Advanced Technology Extended) connector is the primary power interface between a computer’s power supply unit (PSU) and motherboard. First introduced by Intel in 1995, ATX improved on the older AT design and soon became the de facto standard motherboard connector.
The 24-pin ATX connector delivers power from PSUs to motherboards. (Image credit: Computer Hope)
ATX connectors provide several power supply rails, including 3.3V, 5V, and 12V lines to power various motherboard components and expansion cards. They have gone through numerous revisions over the years to provide devices with more power as computing demands increased. Let’s look at some key versions.
Original ATX
The inaugural ATX specification in 1995 introduced a new 20-pin connector with dedicated 3.3V, 5V and 12V rails. This 20-pin interface became widely adopted and replaced previous AT standards.
ATX12V 1.x
In 2000, Intel released the ATX12V 1.x revision targeting power delivery to modern CPUs and APUs, especially the Pentium 4. This introduced an additional 4-pin “P4 connector” carrying 12V power for the processor.
ATX12V 2.x
Released in 2003, ATX12V 2.x further increased 12V power delivery to align with contemporary hardware. The 20-pin connector was replaced by a 24-pin version to power more demanding components. 3.3V and 5V power rails were also reduced as 12V became the norm.
Modern ATX PSUs and motherboards utilize this 24-pin connector with dedicated 12V lines. Additional minor revisions have tweaked power delivery specifications.
EPS Power Connectors
The EPS (Entry-Level Power Supply) connector is an auxiliary interface designed specifically to power computer central processing units (CPUs). Also dubbed the “P8” connector, EPS plugs have either an 8-pin or 4+4 pin design to deliver extra 12V current from PSUs to motherboard voltage regulator modules (VRMs).
/4_plus_4_eps_power_connector-5e9c22ec88c77a00128af140.jpg)
8-pin EPS connectors supply extra power to computer processors. (Image credit: Lifewire)
Introduced in 2003 alongside ATX12V 2.0, EPS connectors replaced earlier non-standardized P4 aux power adapters. They enabled stable power delivery to modern multi-core 64-bit CPUs. EPS plugs are still widely used today for powering high-end processors with extra 12V current above what ATX connectors can provide.
PCI Express Power Connectors
PCI Express (PCIe) is a high-speed expansion card interface that replaced older standards like PCI and AGP. Graphics cards and accelerators often use PCIe to connect to motherboards.
Power-hungry graphics cards in particular may require additional clean 12V power provided directly from PSUs via 6-pin or 8-pin PCIe connectors. This ensures stable power delivery under load to GPUs and video cards.
6+2 PCIe connectors supply supplementary power to graphics cards. (Image credit: Rock Paper Shotgun)
While motherboard PCIe slots provide 75W of power, aux ports allow up to 150W for 6-pin and 225W for 8-pin cables. Modular PSUs began including these connectors specifically for high-end graphics subsystem needs.
SATA Power Connectors
SATA (Serial ATA) connectors provide power supply links to storage devices like hard disk drives (HDDs), solid state drives (SSDs) and optical drives.
Standardized in 2003, these compact 15-pin SATA plugs deliver voltage from PSUs to mass storage devices via thinner, more flexible cabling (enabling easier builds and improved airflow). They superseded bulky legacy 4-pin Molex power adapters used for older parallel ATA/IDE drives.
SATA data cables for transfers combine with 15-pin SATA power connectors. (Image credit: Cablematic)
Designed exclusively for lower-powered storage devices, SATA power connectors can transmit voltages below those used for other auxiliary ports. However they offer plenty of stable current for contemporary HDDs and SSDs.
Legacy Floppy Disk Drive Connectors
If you look closely at many power supply units, you may notice smaller legacy 4-pin floppy disk drive power connectors. These were used to provide voltage to old 5.25” and 3.5” floppy diskette drives.
/flopy-power-connector-5df275a546e0fb0001721eaf.jpg)
Legacy 4-pin floppy drive connectors are rarely used today. (Image credit: Lifewire)
This interface has been obsolete for over a decade now. But many PSUs still integrate floppy power ports due to ubiquitous legacy support. Of course, modern motherboards no longer feature floppy drive headers at all.
These days 4-pin floppy adapters are mostly useless vestigial appendages reminding us of an ancient time before USB flash drives.
Final Words
I hope this guide has helped explain the most common pin connector types you’ll see inside modern desktop computers. These crucial interfaces have evolved over decades along with changing power requirements and interface standards. ATX, EPS, PCIe and SATA connectors now each serve distinct roles in delivering stable power to vital components.
Of course many other proprietary or obscure power connectors exist—but these are the essential ones to know! If you have any other questions about power cables or want to learn more, let me know in the comments.
