If you’ve been assembling or upgrading a PC, you may have come across a Molex cable. But what exactly is it, and what is it used for?
In this article, we’ll explain what a Molex cable is, how it works, and why it’s still found in modern computing and electronics projects.
what is a molex cable
What Is a Molex Cable?
A Molex cable refers to a power cable that uses a Molex connector, originally developed by the Molex company. The term usually refers to the 4-pin peripheral power connector widely used in desktop computers to power internal components.
The classic Molex 8981 connector (often just called “Molex”) features:
4 pins:
Yellow wire: +12V
Black wires: Ground
Red wire: +5V
A white plastic housing with a locking mechanism
It is often connected directly to a power supply unit (PSU) via standard modular or fixed cables.
What Is a Molex Cable Used For?
While newer connectors like SATA have become more common, Molex cables are still used for:
✅ Powering Internal PC Components
Hard drives (IDE/PATA)
Optical drives (CD/DVD)
Case fans
Fan controllers
Older GPUs or expansion cards
✅ Adapters and Modding
Molex-to-SATA adapters
Molex-to-fan hub cables
Custom lighting setups (e.g., LED strips)
✅ DIY Electronics Projects
Robotics, Arduino, and prototyping where 5V or 12V is needed
Why Is It Called “Molex”?
The name comes from Molex Incorporated, the company that developed the connector design. Over time, “Molex” has become a generic term used for a family of power connectors in electronics and PCs—though technically, there are many types of Molex connectors beyond the 4-pin variety.
Molex vs SATA Power Connector
| Feature | Molex | SATA Power |
|---|---|---|
| Pin Count | 4 | 15 |
| Voltage Support | +12V, +5V | +12V, +5V, +3.3V |
| Hot-Plug Support | No | Yes |
| Device Compatibility | Older drives, fans | Modern hard drives, SSDs |
| Connector Size | Larger, more durable | Slim, more compact |
While SATA has largely replaced Molex for hard drives, Molex is still used for fans, legacy drives, and adapters.
Is Molex Still Relevant Today?
Yes—though less common, Molex connectors are still relevant for:
Legacy system maintenance
Custom PC builds with many fans
LED and modding setups
Embedded and industrial electronics
Modern modular power supplies often include a few Molex connectors or cables with Molex headers just in case they’re needed.
Conclusion
So, what is a Molex cable?
It’s a 4-pin power cable used primarily in desktop PCs to provide +12V and +5V power to components like fans, drives, and accessories. Though not as popular as it once was, it remains a valuable part of many builds and repair jobs.
