Molex 4-Pin - The Legacy PC Power Connector

The classic 4-pin power connector (AMP / Mate-N-Lok 1) for IDE drives, fans, GPU pre-2000s and accessories. Replaced by SATA Power but still ubiquitous as a legacy standard.

The Molex 4-pin connector - technically AMP Mate-N-Lok 1 with 4.20 mm pin pitch, but universally known as "Molex" - was the standard PC drive power connector from the 1980s into the early 2000s. Four contacts: yellow = +12 V, black = GND, black = GND, red = +5 V. The connector is bulky, has no latch, no hot-swap support and no 3.3 V rail - all reasons it has been superseded by SATA Power. It remains relevant for case fans, water-cooling pumps, RGB controllers and a few legacy IDE adapters.

Technical Specifications

Standard	AMP / Mate-N-Lok 1
Pins	4
Voltages	+12 V (yellow), +5 V (red), 2x GND (black)
Pin pitch	4.20 mm
Polarisation	Asymmetric chamfered
Latch	None - friction fit only
Typical current	up to 11 A per pin

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Frequently Asked Questions

Is the Molex connector still used in new builds?

Rarely for drives - SATA Power has fully replaced it. But case fans, GPU PCIe adapters, water pumps and RGB controllers often still use the 4-pin Molex form factor for legacy reasons.

Can I splice 12 V from Molex for a custom mod?

Yes, but watch the current rating: 11 A max per pin, so a single Molex can sustain about 100 W on the 12 V rail. Beyond that, use a dedicated PCIe 6 / 8-pin connector.

Why is the Molex prone to coming loose?

No latch - only friction. Combined with stiff 18 AWG wire and gravity in tower cases, vibration over time can pull the connector partially out. Always route Molex cables with strain relief.

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