Internal PC Connectors
The four internal connector families that bring power and data inside a PC chassis: ATX mainboard supply, Molex 4-pin (legacy), S-ATA Power for drives, and the PCI Express bus for expansion cards.
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The Four Internal Power Connectors
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ATX 24-pin
Mainboard master power - 3.3 V, 5 V, 12 V, -12 V, +5VSB, PWR_OK.
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Molex 4-pin
Legacy 5 V / 12 V plug for IDE drives, fans, accessories.
Details →
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S-ATA Power
15-pin modern drive supply (3.3, 5, 12 V, hot-swap).
Details →
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PCI Express
x1 / x4 / x8 / x16 expansion bus. Up to 256 GB/s.
Details →
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Direct Comparison
| Connector |
Pins |
Voltages |
Latch |
Hot-swap |
Typical use |
| ATX 24-pin | 24 (20+4) | 3.3, 5, 12, -12 V, +5VSB | Yes | No | Mainboard |
| Molex 4-pin | 4 | 5, 12 V | No | No | Legacy drives, fans |
| S-ATA Power | 15 | 3.3, 5, 12 V | No (friction) | Yes | Modern HDD / SSD |
| PCIe x16 | 164 | 3.3, 12 V (75 W slot) | Yes | No (slot only) | GPU, NVMe, NIC |
Typical Wiring of a Modern PC
A typical mid-range desktop wires the PSU like this: ATX 24-pin to the mainboard, S-ATA Power daisy-chained to two or three drives, EPS 8-pin CPU supply (electrically Molex Mini-Fit Jr. with different polarisation), PCIe 6+2 / 8-pin for the GPU, and an old Molex 4-pin kept for case fans, water pumps and RGB controllers.
Frequently Asked Questions
Can I use a 20-pin PSU on a 24-pin mainboard?
Mechanically yes, but most modern boards (especially with PCIe GPUs) need the additional 12 V rails of the 24-pin connector. Use a 20+4 split cable or upgrade the PSU.
Are Molex-to-SATA adapters safe?
For low-power consumer drives yes. For 3.5" enterprise drives or arrays, prefer native S-ATA Power - cheap adapters have caused fires under sustained load.
What is the new 12VHPWR connector?
Introduced with ATX 3.0 and PCIe 5.0 - a single 16-pin connector (12 power + 4 sense pins) that delivers up to 600 W to high-end GPUs. Replaces the cluster of two or three 8-pin PCIe connectors.
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Procurement: Phone +49 7666 88499-0 · sales@industry-electronics.com · PSUs, internal cables, expansion cards.
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