Guide to Power Supply Connectors Pinouts Selection Safety

Have you ever felt overwhelmed by the variety of power connectors in your computer? From the 24-pin ATX motherboard connector to 8-pin EPS CPU power and 6+2-pin PCIe graphics card connectors, these components can be confusing. More critically, incorrect connections may lead to system failures or even hardware damage. This guide explores power connector specifications, selection criteria, and safety protocols to help you build and maintain systems with confidence.

ATX (Advanced Technology eXtended) power supplies dominate desktop computing. Their connectors have evolved from 20-pin to 24-pin configurations to meet increasing power demands.

Introduced with the ATX12V 2.0 specification, the 24-pin connector provides additional power for PCI Express slots. Compared to legacy 20-pin connectors, it adds more 3.3V, 5V, 12V, and ground lines, eliminating the need for auxiliary cables. The connector features a foolproof design that prevents incorrect insertion.

24-pin connectors maintain backward compatibility with 20-pin motherboards. When connecting to a 20-pin socket, the extra 4 pins remain unused. The design ensures proper orientation, though users should verify the unused pins don't contact other components.

Originally designed for workstations, the 8-pin EPS12V connector now powers high-performance CPUs. Its keyed design prevents incorrect insertion, with four square and four rounded pins matching the motherboard receptacle.

Modern graphics cards often exceed the 75W available through PCIe slots, requiring supplemental power:

• 6-pin PCIe: Officially provides 75W (though often capable of more)
• 8-pin PCIe: Delivers up to 150W
• 6+2-pin: Flexible design works with both connector types

The venerable 4-pin Molex connector persists in modern systems for fans, lighting, and adapters. Each connector provides +5V and +12V power with a maximum current of 5A per rail.

SATA power connectors introduced support for 3.3V (though rarely used) while maintaining 5V and 12V rails. The 15-pin design prevents reverse insertion and supports up to 4.5A per voltage rail.

When building or upgrading systems, always verify connector compatibility and orientation before applying power. Proper cable management not only improves airflow but reduces the risk of accidental disconnections or short circuits. With this knowledge, you can confidently navigate the complex landscape of PC power delivery.