Find PC connector pinouts instantly with this free PC Connector Pinout Reference. View motherboard, power supply, storage, cooling, USB, display, and internal PC connector pin layouts for computer repair, assembly, engineering, and education.
Bench Testing an ATX PSU
Short the green /PS_ON wire (Pin 16 on a 24-pin block or Pin 14 on a 20-pin block) to any black COM ground pin. This turns on the power supply without a motherboard.
Serial Null Modem Cable
To establish direct PC-to-PC communication via DE9 ports, cross-connect Pin 2 (RXD) to Pin 3 (TXD) and tie Pin 5 (GND) straight through.
Custom eSATA to SATA Cable
Adaptors map eSATA differential transmit (Pins 2/3) and receive (Pins 5/6) lines directly to standard SATA internal connectors with extra shield grounds.
USB 3.0 Backward Compatibility
Pins 1 to 4 provide legacy USB 2.0 pathways, while Pins 5 to 9 carry SuperSpeed differential signals (TX and RX lanes), allowing seamless connection updates.
Computer power distribution networks and communication lines rely on low-impedance pathways and balanced signal pairs to run stable high-frequency networks. Standard ATX power supplies deliver multiple voltage rails (+12V, +5V, +3.3V, -12V, and standby +5VSB) through standardized 20-pin and 24-pin mainboard blocks. Differential signaling protocols, used in USB 3.0, DisplayPort, and Serial ATA interfaces, transmit data via inverted signal pairs to reject environmental electromagnetic interference (EMI).
This reference guide organizes wiring configurations, line assignments, and safety margins for ATX power supplies, serial buses, storage connections, and legacy ports.
Finding accurate pin layouts is essential for system integrators, PC builders, diagnostic technicians, and hardware designers. Using standardized connectors prevents controller errors, startup loops, and permanent motherboard damage.
Always verify active line currents before modifying power cables. Correct electrical connections protect your system and improve data transfer stability.
The /PS_ON pin (Pin 16 on 24-pin plugs) is a low-active signal line. When the motherboard pulls this pin to ground (zero volts), the power supply turns on its main DC voltage output rails.
The -5V rail was originally required for ISA expansion cards used in older IBM-compatible PCs. Intel removed -5V from the ATX specification in 2004 (v2.01) because modern motherboard buses no longer use it.
The Lightning connector contains an integrated authentication chip that detects orientation. The chip dynamically maps active lane pins (L0p, L0n, L1p, L1n) to match whichever side is facing up.
The Configuration Channel (CC) pins detect plug orientation, determine cable orientation, and negotiate USB Power Delivery (PD) voltage levels between connected devices.
The standard eSATA interface is designed purely for high-speed data transfer. Connecting external drives requires either an external power adapter, a dual-connection cable, or an active Power-eSATA port.
MIDI uses optocouplers to isolate transmitting and receiving devices. Isolating connections electrically prevents ground loops, hum, and digital signal interference in studio audio networks.
PC Connector Pinout Reference is a free online calculator tool. Use it to get instant, accurate results for your electronics calculations.