> ## Knowledge Base Index > Fetch the complete knowledge base index at: https://help.moddiy.com/sitemap.xml > Use this file to discover available pages before exploring further. > Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash). # What is a Pinout Specification? ## Understanding Computer Cable & Connector Diagrams In computer hardware, a **pinout specification** (or simply "pinout") is a technical diagram, reference table, or document that details the specific function, signal type, or voltage level assigned to every individual pin inside an electrical connector, wire, or cable interface. Whether dealing with power supply cables, motherboard headers, or data buses, a pinout acts as the definitive blueprint for how electrical power and digital communication safely flow between components. --- ## What Information Does a Pinout Specification Contain? A complete pinout specification goes beyond just showing where wires go; it defines the precise electrical and logical properties of each contact point: 1. **Pin Numbers & Orientation**: A mapped physical key (usually viewed from the front/mating face of the connector or rear wire entry) designating Pin 1 through Pin *N*. 2. **Voltage & Power Output Specs**: Identifies DC voltage rails supplied across specific lines (e.g., +12V, +5V, +3.3V, or +5VSB standby power). 3. **Ground (GND) Lines**: Specifies common ground return paths essential for circuit completion and voltage reference stability. 4. **Signal & Data Lines**: Designates lines carrying high-speed differential signals, logic levels, clock signals, or control channels (e.g., USB `D+`/`D-`, PCIe data lanes, or I²C/SMBus communication). 5. **Sense & Control Pins**: Modern high-power interfaces (like the 16-pin 12VHPWR / 12V-2x6 GPU connectors) include low-voltage sense pins (e.g., `SENSE0`, `SENSE1`) to dynamically negotiate maximum allowable wattage between the PSU and graphics card. 6. **Keying & Physical Geometry**: Details mechanical keying (square vs. chamfered pin housings) to physically prevent backwards or mismatched insertion. --- ## Key Types of Computer Pinouts 1. **Power Supply Units (PSU Cables)** * Power pinouts specify the DC output voltage and maximum current capacity for modular power cables and component power ports. * **24-Pin ATX Main Power**: Supplies mainboard logic and peripheral power via +12V, +5V, +3.3V, -12V, +5VSB, along with control signals like `PS_ON#` (power on switch) and `PWR_OK` (Power Good signal). * **EPS / ATX12V 8-Pin CPU**: Delivers dedicated +12V power directly to the motherboard's VRMs (Voltage Regulator Modules) for processor power. * **PCIe 6+2 Pin & 12VHPWR (12+4 Pin)**: Supplies dedicated +12V power to high-draw expansion cards and GPUs. 2. **Peripheral & Storage Cables** * **SATA Power**: Uses a 15-pin wafer-style connector carrying three primary voltage supply lines (+3.3V, +5V, and +12V) alongside dedicated ground pins. * **Molex (4-Pin Legacy Power)**: Provides +12V (Yellow) and +5V (Red) separated by two central Ground lines (Black). 3. **Data & Communication Interfaces** * **USB Internal Headers**: Maps +5V (VBUS), Data Minus (`D-`), Data Plus (`D+`), and Ground (`GND`). * **Front Panel Headers (F_PANEL)**: Maps low-voltage mainboard jumper pins for the chassis Power Switch (`PWR_BTN`), Reset Switch (`RST`), Power LED, and Storage Activity LED (`HDD_LED`). --- ## Why Pinout Specifications Matter in PC Hardware & Custom Cabling * **Component Safety & Overvoltage Prevention**: Connecting a high-voltage rail (e.g., +12V) into a low-voltage logic line (e.g., +3.3V or a signal line) will instantly damage microcontrollers, drives, or motherboards. * **Modular PSU Compatibility**: While component-side connectors (ATX, EPS, PCIe) follow strict industry standards set by Intel/PCI-SIG, **the pinouts on the modular power supply housing itself are NOT standardized**. Different manufacturers—and even different series from the same brand—route voltages to different modular sockets. Swapping modular cables between incompatible power supplies without verifying the pinout can cause catastrophic hardware failure. * **Troubleshooting & Multimeter Testing**: Engineers and PC builders rely on pinout tables to perform manual voltage testing using a digital multimeter (DMM) or oscilloscope to verify PSU output tolerances under load. --- ## How to Obtain Pinout Specifications Finding accurate pinout specifications depends heavily on the manufacturer and the type of hardware component: 1. **Public Downloads from Vendors**: * Some hardware vendors publish pinout diagrams directly on their product pages, user manuals, or support downloads. * **Example**: Power supply manufacturers like **Lian Li** provide downloadable pinout diagrams for their modular PSUs directly on their official website, making it easy for users and custom cable makers to verify wire positions. 2. **Direct Contact with Vendor Support**: * If a vendor does not publish the pinout spec publicly on their website, you can reach out directly to their technical support or engineering team to request the official pinout documentation. * When contacting support, specify the exact model name, hardware revision, and connector type needed. 3. **Manual Pinout Mapping (Multimeter Trace)**: * When official documentation is unavailable from the vendor, engineers and custom cablers often manually map pinouts using a digital multimeter set to continuity mode (or measuring voltage rails on an active unit) to trace connections pin-by-pin. --- ## Pinout Examples ![ATX Pinout](https://storage.crisp.chat/users/helpdesk/website/-/1/2/7/a/127ac00d28a66e00/atx_1dvse1d.jpg) ![Antec Pinout](https://storage.crisp.chat/users/helpdesk/website/-/1/2/7/a/127ac00d28a66e00/antec_y9m5n3.jpg) ![Cooler Master Pinout](https://storage.crisp.chat/users/helpdesk/website/-/1/2/7/a/127ac00d28a66e00/coolermaster_dwhyuy.jpg) ![USB Pinout](https://storage.crisp.chat/users/helpdesk/website/-/1/2/7/a/127ac00d28a66e00/usb_97j15s.jpg)