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Yes. A standard ATX power supply’s 20+4-pin motherboard cable is designed to become one 24-pin plug. Join the detachable four-pin section to the 20-pin section, align the keyed housing and retaining latch with the motherboard’s 24-pin socket, then press the complete connector in evenly. The detachable section is part of the motherboard main-power cable—not the separate CPU 4-pin or 4+4-pin cable.
What “20+4 pin” means
A 20+4-pin lead is a split version of the ATX motherboard main-power connector. Its 20-pin block and adjacent four-pin block are designed to lock together as a 24-pin plug for modern motherboards. The split design also allows the same cable to serve an older motherboard with a compatible 20-pin socket.
When your motherboard has a 24-pin socket, use both sections together. Do not leave the four-pin section hanging aside.
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- Shut down and disconnect power. Turn off the computer, switch the PSU to O if it has a rocker switch, unplug the AC cable and press the case power button briefly to discharge residual power.
- Identify the correct PSU lead. Find the fixed or modular cable labeled ATX, Motherboard or MB. Do not use a CPU/EPS lead, PCIe lead or peripheral cable.
- Join the two sections. Hold the 20-pin block and detachable four-pin block side by side so their keyed housings form one straight 24-pin connector. Keep the four-pin block alongside the correct end of the 20-pin block; do not rotate it.
- Match the keying and latch. Position the connector over the motherboard’s 24-pin socket with the cable latch aligned to the socket’s retaining tab. The pin shapes and blocked positions should match without force.
- Press evenly until seated. Push on the connector body, not the wires, until the latch engages and no visible gap remains between plug and socket. If it resists, remove it and recheck orientation rather than applying more pressure.
- Reconnect and test. Reconnect AC power and start the system. If it does not power on, switch off again before inspecting the connection.
The four-pin section is not CPU power
Motherboards normally have two different power areas:
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- 24-pin ATX main power: the large socket at the board edge. It receives the joined 20+4-pin connector.
- CPU power: a separate four-pin ATX12V socket or an eight-pin socket supplied by a 4+4-pin EPS/CPU lead, usually near the processor socket.
Both cables can contain four-pin sections, but they are not interchangeable. Never insert a square CPU 4-pin plug or half of a 4+4 CPU plug into the motherboard’s 24-pin socket. Use the motherboard and PSU labels and the board layout in its manual.
20+4-pin versus a PSU with only 20 pins
| PSU main connector | Use on a 24-pin motherboard | What to do |
|---|---|---|
| 20+4-pin split lead | Designed to form a 24-pin plug | Join both sections and install the complete connector. |
| Native 24-pin lead | Designed for the socket | Install it as one keyed connector. |
| 20-pin-only lead | Model-specific; not universally supported | Check the exact motherboard manual. If support is not documented, use a PSU with a native 24-pin or 20+4-pin lead. |
A 20-pin-only plug is a different situation from a 20+4 cable with its four-pin section detached. Some boards document a permitted 20-pin installation. For example, the ASRock H61M-GS manual describes a specified alignment for using a traditional 20-pin ATX PSU on that board’s 24-pin connector. That instruction applies to that model and its documented conditions; it does not establish compatibility for every 24-pin motherboard.
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Modular PSU precautions
With a modular power supply, identify both ends of the cable before connecting it. The PSU-side socket arrangement is not the same as the motherboard-side 24-pin plug, and modular cables are not safely interchangeable merely because their connectors look similar.
- Use the cable supplied with that exact PSU.
- If replacing a cable, use one explicitly approved for the same PSU model or series.
- Follow the PSU manufacturer’s wiring diagram and the motherboard manual.
- Never force a modular connector into a socket with a different keying or pin layout.
Do you need an adapter?
No adapter is normally required for a standard 20+4-pin ATX cable: the two sections are intended to join directly and fill a 24-pin socket. An adapter should not be the default solution for a 20-pin-only PSU. First verify the motherboard’s documented support and the system’s power requirements; replacing the PSU with a suitable native 24-pin or 20+4-pin model is the straightforward option when compatibility is uncertain.
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Checks when the computer will not start
The connector will not seat
- Confirm that the four-pin section is beside the 20-pin block, not above or below it.
- Check the latch, blocked positions and pin shapes against the socket.
- Make sure you are using the motherboard lead, not a CPU or PCIe cable.
- Inspect for a damaged housing or bent motherboard socket; stop if anything appears damaged.
The system has no power after installation
- Disconnect AC power and reseat the complete 24-pin connector until its latch engages.
- Verify the PSU rear switch, wall outlet and AC cable.
- Confirm that the separate CPU 4-pin or 4+4-pin power lead required by the motherboard is also connected to the CPU-power socket.
- Check the motherboard manual for any model-specific requirement when using a 20-pin-only PSU.
The PSU is modular and a replacement cable was used
Remove the replacement cable unless the PSU maker explicitly approves it for that exact model. A matching-looking modular plug does not guarantee matching wiring.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Choosing a replacement PSU
If your current supply lacks the connector your board requires, compare the exact motherboard socket, the PSU’s included cable set, the total power needs of the complete system and the manufacturer’s documentation. The connector type alone does not determine the wattage needed, so do not choose a capacity without evaluating the processor, graphics card and other components.
Quick Recap
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