A fan hub is a small board that splits one power source and one control signal into several fan connectors. A motherboard header is the connector on the board itself, and for most builds with four or fewer fans, the header is the better choice. It gives each fan a direct control path, reads speed back for monitoring, and avoids an extra board in the case. Use a hub when your board runs out of headers or when the header positions do not suit your cable layout.
Current figures and speed behavior below come from typical specifications and common board designs. Always check your motherboard and hub manuals for the exact ratings on your hardware.
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What a fan hub and a motherboard header do
A motherboard fan header is a four-pin or three-pin connector that provides power to a fan and, on four-pin models, a PWM control signal. The board reads the fan’s tachometer signal and can change its speed through BIOS or software. Each header is usually linked to a fan curve, so you can tie a fan’s speed to the temperature of the CPU, the GPU or the case. This direct link is why headers remain the standard for most builds.
A fan hub takes its power from a SATA or Molex connector, or from a motherboard header, and distributes it to several fan connectors on the hub. Many hubs also accept a control signal from one motherboard header and pass that signal to every fan on the hub. Some hubs add their own fan speed knob or temperature sensor, which lets you control the group without touching the BIOS. Because all fans on the hub share one control signal, they usually move together.
The distinction matters because it changes how you can tune the system. With separate headers, you can run the front intake fans faster during gaming and keep the top exhaust fan quieter. With a hub, you get more physical connectors but less independent control. Think about which fans you want to tune before choosing the hub route, since a hub may force two fans with different jobs to run at the same speed.
Current and power limits on fan headers
Every motherboard header has a current limit, and exceeding it can damage the board or cause fans to stop. Manufacturers often rate system fan headers around 1A, which is about 12W at 12V, although the exact number varies by board and by header. The CPU fan header is often rated higher because it is designed for larger coolers. Look for the rating in your motherboard manual, since it is not always printed on the board itself.
Fan current draw depends on size, speed and design. A typical 120mm fan may draw only a few hundred milliamps at full speed, while a high-static-pressure model for a radiator can draw considerably more. Many fan specifications list current in amps at a stated RPM, so add the draw of every fan on a single header or hub before you connect them. If the total is close to the rating, split the fans across another header or a hub with its own power source.
Power draw is different from fan count. Four quiet fans may draw less than two high-speed fans, so counting fans alone is not a reliable way to plan. A safe approach is to keep your total draw comfortably below the header’s rating, leaving headroom for fan speed spikes during startup. Startup current is higher than steady-state current, so a fan that runs fine at low speed can still stress a header on power-on.
Control: PWM and fan curves
Control is where a motherboard header usually wins. A four-pin PWM header lets the board vary fan speed by changing a pulse-width signal, which gives smoother control than voltage-based control. Each PWM header can follow its own fan curve in BIOS or software, so the intake fans can respond to GPU temperature while the exhaust fan responds to CPU temperature. Setting different curves for each fan group is the basis of a quiet, well-balanced case.
A fan hub with PWM support can still deliver useful control, but it reduces your options. Every fan connected to the hub follows the same signal, so you can set one curve for the whole group. That is acceptable for a set of intake fans that should behave the same way. It is less suitable for a mix of intake and exhaust fans, where different temperature sources should drive different speeds. If you use a hub, plan the groups so each one needs the same behavior.
For a step-by-step guide to building a curve in BIOS or monitoring software, see our article on how to set a custom fan curve. The principle is the same whether you use a header or a hub: pick the temperature source, set low speeds for quiet operation, and ramp up under load. A well-tuned curve often matters more to noise levels than the choice of hub or header.
Passive splitters and powered controllers
A passive splitter is a cable that divides one fan connector into several without any electronics. It only passes power, so the fans on it run at whatever speed the voltage provides. Connected to a DC-controlled header, a passive splitter can allow voltage-based speed control, but connected to a PWM header it may run fans at full speed all the time. Passive splitters are inexpensive, and they suit fixed-speed fans in a build where you do not need control.
A powered fan hub has its own power input, usually from a SATA or Molex connector, and it can regulate the fans it powers. Some powered hubs include a manual speed knob, while others accept a PWM signal from the motherboard. Powered hubs cost more, but they keep the motherboard header’s current load low and can add temperature-based control. They are the better choice when you have many fans or when the board cannot supply enough current.
The main point is that the word hub can mean very different products. Before you buy, check whether the product is passive or powered, whether it accepts a PWM control signal, and how many fans it supports on each channel. A cheap passive splitter may look similar to a powered hub, but the behavior is completely different, and mixing them up is a common source of noise complaints. If you are still choosing the fans themselves, see our best case fans for airflow roundup.
Side-by-side comparison
The table below compares the three typical options for connecting case fans. Use it as a planning checklist, then confirm the details in each product’s manual.
| Option | Power source | Speed control | Best for | Main drawback |
|---|---|---|---|---|
| Motherboard header | Board header, rated around 1A on many system headers | Individual PWM or DC curves | Four or fewer fans, per-fan tuning | Limited number of headers |
| Powered PWM fan hub | SATA or Molex, often plus a control header | One signal for all connected fans | Many fans, simple grouped control | Shared curve, extra cost and cable |
| Passive splitter | Taken from the fan header | None, or voltage-based only | Fixed-speed fans, budget builds | Full speed and noise, no curves |
In most builds, the best answer is a mix. Use the board’s headers for the main intake and exhaust fans so you can tune them separately. Add a powered hub for extra case fans or RGB controllers that do not need individual curves. Avoid using a passive splitter on any fan you want to control, since it removes the benefit of the header.
Cable routing and case layout
Layout affects how easily you can connect fans. Motherboard headers are fixed on the board, so the fan cable must reach from its fan position to the header. In a case with a top-mounted radiator or front fans, that route can be long, and the cable can cross the GPU or RAM area. Plan the header positions before installing the board, and measure the route from each fan to its header so the cable does not pull on the fan.
A hub simplifies routing in some cases. You can mount the hub in a convenient place, such as the rear of the case or behind a panel, and run one cable from the hub to the header. Fans then connect to the hub at short distances. However, the hub’s power cable must reach a SATA or Molex connector, and that adds one more cable to manage. Use cable ties or velcro straps to keep the hub and its wires tidy.
Keep the airflow path in mind as you route cables. Cables that block the intake or the exhaust reduce cooling, even if the fan connection is correct. Route the fan cables along the back of the motherboard tray and keep them away from the fan blades. For the broader airflow picture, see how to improve PC airflow. For a broader approach to routing and tidy cabling, see how to plan cable management, which covers the sequence to follow during a build.
Troubleshooting: fans not responding or spinning wrong
If a fan does not respond to a curve, check the connection first. A four-pin fan on a header that expects three pins, or a three-pin fan on a PWM header, may spin at full speed or not respond to control. Confirm that the fan is on the correct header type and that the header is set to PWM or DC mode in BIOS. A fan that is on a passive splitter may not respond to the header at all.
If several fans stop together, suspect the header or the hub. A hub with a failed power input or a loose SATA connector can stop every fan connected to it. A header rated too low for the fans attached to it can trigger a fault or shut the fans off. Measure the total current draw and compare it with the rating, and move a few fans to a second header or a powered hub to see whether the problem follows the load.
If fans run at the wrong speed, check the curve and the sensor. A curve tied to a sensor that does not change will keep the fan at a fixed speed. Also check whether the fan is on a hub that shares its signal with other fans, since that can force all of them into the same behavior. Make one change at a time, and recheck the fan’s speed under load, so you know which fix worked.
Frequently asked questions
What is the difference between a fan hub and a motherboard header?
A motherboard header is the connector on the board that supplies power and fan control signals to one fan or one group of fans. A fan hub is a separate small board that takes power and a control signal from the motherboard or a PSU cable and splits it into several fan connectors. The header gives you direct control and monitoring, while the hub gives you more connection points. Choose the header when it is enough, and add a hub when you run out of headers.
Is a fan hub better than using motherboard headers?
Not in general. A hub is useful when you have more fans than headers, or when your board’s headers are in awkward positions for the case layout. However, a hub sends one control signal to all connected fans, so every fan on it runs at the same speed. If you want each fan to follow its own curve, connect them to separate headers instead of routing them through a hub.
Can a passive fan splitter replace a fan hub?
A passive splitter only divides the power cable and does not control fan speed. Fans on a passive splitter run at full speed whenever the system is on, unless they connect to a voltage-controlled header. That produces more noise and offers no fan curves. Use a powered fan hub with PWM control, or a motherboard header, if you want speed control. Passive splitters are acceptable only for fans you want at a fixed high speed.
How many fans can one motherboard header power?
It depends on the header’s current rating, which is often around 1A, or about 12W, for system fan headers. Many modern fans draw far less, so a header can power several small fans, but a heavy set of high-static-pressure models can exceed its limit. Check your motherboard manual for each header’s rating, add up the fans’ current draw from their specification sheets, and use a hub or a second header if you approach the limit.
Does a fan hub need to connect to the motherboard?
Many powered fan hubs connect to a motherboard header for the control signal and to a SATA or Molex power connector for the fan power, although some models use only the power connector and run in fixed-speed mode. A hub with PWM control needs the control cable to adjust speed. Check the hub’s manual before you buy, and confirm which connectors it requires so you do not end up with fans that spin at full speed or not at all.
