PSU Connectors Explained: 24-Pin, EPS, PCIe, and 12VHPWR

PSU connectors are the cable ends a power supply uses to deliver regulated DC voltage to the motherboard, processor, graphics card, drives, and peripherals. Each connector has a defined pin count, voltage set, and current rating, and each powers a specific part of the system. A power supply ships with the 24-pin ATX connector for the motherboard, the 4+4 EPS connector for the processor, the 6+2 PCIe connector for the graphics card, the SATA power connector for drives, the Molex connector for legacy devices, and on modern units the 12VHPWR or 12V-2×6 connector for high-power graphics cards.

This guide defines each connector, states its pin count and the wattage it carries, explains what it powers, covers proper seating and the 12VHPWR melting issue, and warns against mixing modular cables between brands. A table pairs each connector with its pins, target, and typical wattage.

What Are PSU Connectors?

PSU connectors are the standardized cable terminals through which a power supply delivers its regulated 3.3-volt, 5-volt, and 12-volt outputs to each component in the system. A power supply converts wall AC into several DC voltages, and the connectors carry those voltages over dedicated cables to the parts that need them. Each connector type has a fixed pin layout, a defined set of voltage and ground pins, and a current rating that limits the power it can carry safely.

The main connectors are the 24-pin ATX for the motherboard, the 4+4 EPS for the processor, the 6+2 PCIe and the 12VHPWR or 12V-2×6 for the graphics card, the SATA power for drives, and the Molex for legacy devices. The pinout that plugs into a component is standardized across the industry, so any power supply’s 24-pin cable fits any motherboard. The connectors carry the output of the AC-to-DC conversion process to the components that consume it.

What Is the 24-Pin ATX Connector?

The 24-pin ATX connector is the main motherboard power connector that delivers 3.3-volt, 5-volt, and 12-volt power to the motherboard and its onboard components. The 24-pin connector, defined by the ATX specification, supplies the motherboard’s voltage regulators, the chipset, the memory, the PCIe slots, and the onboard controllers. The connector splits into a 20-pin and a 4-pin section so it can serve older 20-pin boards, though all current motherboards use the full 24 pins.

The connector carries multiple rails: several 12-volt pins, several 5-volt pins, several 3.3-volt pins, and the corresponding grounds, plus the power-on and power-good signal pins that let the motherboard control the unit. The 24-pin connector is the single largest connector on the power supply and is always required, because no system runs without motherboard power.

The connector seats with an audible click from its retention latch, confirming full insertion. The article on how a motherboard distributes power explains where these rails travel on the board.

What Is the EPS CPU Connector?

The EPS connector is the 4+4-pin 12-volt connector that supplies dedicated power to the processor through the motherboard’s CPU voltage regulator. The EPS connector, often labeled CPU or ATX12V, delivers 12-volt current directly to the voltage regulator module that feeds the processor, separate from the 24-pin connector. The connector splits into two 4-pin halves so it can serve as a single 4-pin connector for low-power boards or a full 8-pin for standard boards.

High-end motherboards add a second EPS connector, an 8+4 or dual-8 arrangement, to supply the higher current a high-core-count or overclocked processor draws. A single 8-pin EPS connector carries up to about 235 to 300 watts depending on the cable gauge, sufficient for most processors.

The EPS connector must be fully seated, because the processor draws heavy current through it and a partial connection generates heat. A build with a high-end processor should populate every EPS connector the motherboard provides.

What Is the PCIe Power Connector?

The PCIe power connector is the 6+2-pin connector that supplies supplementary 12-volt power to a graphics card beyond the 75 watts the PCIe slot provides. The PCIe expansion slot delivers up to 75 watts, but a graphics card that draws more requires direct power from the unit through one or more PCIe connectors. The 6+2 connector combines a 6-pin section, rated for 75 watts, with an additional 2-pin section that upgrades it to an 8-pin rated for 150 watts.

A card needing 225 watts uses two 8-pin connectors plus the slot, and a card needing 300 watts uses two 8-pin connectors at full draw. The splittable 6+2 design lets one cable serve either a 6-pin or an 8-pin socket on the card.

Each 8-pin PCIe connector carries 150 watts, so the number of connectors a card requires scales with its total board power. The guide on choosing a graphics card relates these connector counts to the card’s power draw.

What Is the 12VHPWR and 12V-2×6 Connector?

The 12VHPWR connector is a 16-pin PCIe 5.0 power connector that delivers up to 600 watts to a high-power graphics card over a single cable, and the 12V-2×6 is its revised, safer version. The PCI-SIG 12VHPWR connector, introduced with the ATX 3.0 standard, replaces the multiple 8-pin PCIe cables a high-end card would otherwise need, carrying up to 600 watts through twelve power pins plus four sideband signal pins that report the cable’s power capacity. The four sideband pins let the graphics card detect how much power the cable and unit can supply.

The revised 12V-2×6 connector, part of ATX 3.1, keeps the same 600-watt capacity but shortens the four sense pins and lengthens the power pins, so the power pins must seat fully before the connection registers as complete. This change addresses the seating problem behind early 12VHPWR failures.

A current high-power graphics card, such as a flagship RTX model, draws its full power through this single connector. A native ATX 3.0 or 3.1 cable is preferred over an adapter for reliable seating.

What Are the SATA and Molex Connectors?

The SATA and Molex connectors are the peripheral power connectors that supply drives, fans, and legacy devices, with SATA powering modern storage and Molex serving older hardware:

• The SATA power connector is a flat 15-pin connector that delivers 3.3-volt, 5-volt, and 12-volt power to SATA solid-state drives, hard drives, and optical drives, and is the standard storage power connector on every current build.
• The Molex connector is an older 4-pin connector that delivers 5-volt and 12-volt power to legacy hard drives, fans, fan controllers, and some accessories, and remains present for backward compatibility.
• The SATA-to-Molex and Molex-to-PCIe adapters convert between connector types but should be used cautiously, because an adapter can exceed a connector’s current rating if it feeds a high-power device.
• The floppy connector, a small 4-pin connector, is a legacy output that some units still include for old peripherals and certain fan controllers.

SATA power connectors are arranged several per cable, so one cable powers multiple drives in a daisy chain, which suits a build with several storage devices. Molex connectors persist mainly for case fans, fan hubs, and older accessories that predate SATA power.

A build should power a graphics card only through proper PCIe or 12VHPWR connectors, never through a Molex adapter feeding a high-current load, because the Molex connector and its adapter are not rated for the current a modern card draws. Matching each device to its intended connector keeps the current within the connector’s rating.

How Do You Seat PSU Connectors Properly?

You seat a PSU connector properly by pushing it fully into the socket until the retention latch clicks, confirming every pin makes contact before applying power. A connector that is not fully seated makes partial contact, which concentrates the current through fewer pins and raises resistance at the contact, generating heat. Every keyed connector has a latch or clip that engages when the connector is fully inserted, and the click confirms the seating.

The 12VHPWR and 12V-2×6 connector demands particular care, because its 600-watt capacity through a compact connector leaves little margin for a partial connection. Early 12VHPWR cables suffered melting when the connector was not fully seated or was bent sharply near the connector, which forced the current through a subset of pins and overheated them. The 12V-2×6 revision addresses this by requiring the power pins to seat before the connection registers.

A build should insert each connector straight, confirm the latch clicks, and avoid bending the 12VHPWR cable within about 35 millimeters of the connector. Proper seating prevents the localized heating that damages connectors.

Why Should You Not Mix Connectors Between PSU Brands?

Mixing modular cables between power supply brands is dangerous because the connector that plugs into the unit’s modular socket is not standardized, so a cable from one brand can route voltage to the wrong pin on another brand’s unit. The end of a modular cable that plugs into a component, such as the 24-pin or PCIe end, follows the industry standard, but the end that plugs into the power supply’s modular socket is proprietary to each manufacturer and sometimes each model. A cable from a different unit may place 12-volt power where the unit expects ground, which shorts the connected component and can destroy the motherboard, graphics card, or power supply.

The safe rule is to use only the cables supplied with the specific power supply, or replacement cables the manufacturer verifies for that exact model. This warning applies to every modular connector, and a build should never assume two brands’ modular cables are interchangeable. The guide on modular and non-modular power supplies covers the pinout risk in further detail.

PSU Connector Reference Table

The table below lists each power supply connector with its pin count, the component it powers, and the typical wattage it carries.

Key Takeaways

• The 24-pin ATX connector powers the motherboard with 3.3-volt, 5-volt, and 12-volt rails and is always required.
• The 4+4 EPS connector supplies dedicated 12-volt power to the processor, with high-end boards using two connectors.
• The 6+2 PCIe connector adds 150 watts per 8-pin to a graphics card beyond the 75 watts the slot provides.
• The 12VHPWR and 12V-2×6 connector delivers up to 600 watts to a high-power GPU over a single 16-pin cable.
• SATA and Molex connectors power drives and legacy devices, while adapters must stay within their current rating.
• Proper seating until the latch clicks prevents the localized heating behind the 12VHPWR melting issue.

Last Thoughts on PSU Connectors

PSU connectors deliver the power supply’s regulated voltages to each part of the system, and each connector has a defined pin count, target, and wattage. The 24-pin ATX connector powers the motherboard, the 4+4 EPS connector powers the processor, the 6+2 PCIe connector adds 150 watts per 8-pin to a graphics card, and the 12VHPWR or 12V-2×6 connector carries up to 600 watts to a high-power card over a single cable. The SATA and Molex connectors serve drives and legacy devices within their current ratings.

Proper seating until the retention latch clicks prevents the localized heating behind the 12VHPWR melting issue, and modular cables must never be mixed between brands because socket pinouts are not standardized. The computer hardware guide connects these connectors to the rest of the build, and the guide on choosing a power supply explains which connectors a given system requires.