[SOLVED] How many fans can run off a single motherboard connector?

Jul 28, 2019
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Hi not sure if my motherboard is capable of putting a 3 way pwm splitter onto a single header under CHA_FAN2 would it damage the motherboard reason i want to put them in that header because my case carbide 275r comes with 2 x pre-installed fans and i want those two fans on to the CHA_FAN1. I am using the thermaltake Riing 12 sync 3 x fans and the motherboard is a b450m-plus gaming matx
 
This is a fine example of why I complain about the way various makers use or misuse the terms. But I have to concede that the way I use the words is not decreed by anybody.

To me, a fan SPLITTER is the simple device that connects several fans in parallel to the signals from a host mobo fan header, and that's all it does. It has NO connection to any other power source, so the power for ALL of the fans on a SPLITTER must come from the fan header and is subject to that header's limit, normally 1.0 A max total. A fan HUB is a different device and can be identified by the fact that it has a third type of connection - one arm that MUST be plugged into a power output (either 4-pin Molex or SATA) from the PSU. That is the source of power for ALL of the fans connected to the Hub, and it draws NO power from the host header. It does collect the PWM signal from the header and distribute that to all of its fans, but that does not overload that header line. And it does return to the header the speed signal from ONE of its ports, just as a Splitter does. However, since the HUB merely distributes the PWM signal to its fans via Pin #4, and also a fixed +12 VDC power source on Pin #2 for all its fans, it can ONLY control the speed of 4-pin (PWM type) fans and ONLY if it gets the PWM signal from the host header. Thus a HUB can NOT control the speed of any 3-pin fan, no more than a PWM Mode mobo header can.

A 3-pin fan can ONLY be controlled for speed if its mobo header is using the older Voltage Control Mode in which changing the VOLTAGE on Pin #2 is the MODE of controlling speed. A 4-pin fan normally receives instead a fixed 12 VDC supply on Pin #2 and an additional PWM signal which is used inside the fan by a special chip to modify the current from that power source through the windings to effect control of fan speed. So the rule is (IF you use my way of labeling these two different devices) you can use a HUB only with a mobo header that is using PWM Mode to control, and ONLY if the fans are all of the 4-pin PWM type that has the special chip to use that signal. IF you are using 3-pin fans the mobo header can ONLY control their speeds if it is using the older Voltage Control Mode (aka DC Mode), and that means you can NOT use a HUB for this situation, you must use a SPLITTER instead. Let me say right here that I know of ONE Hub that does not follow this "rule". The Phanteks PWM Hub is different because it "converts" from the PWM system it MUST have from its host header and creates its own group of six 3-pin ports that DO use the older Voltage Control Mode and thus CAN control 3-pin fans. Also we should note that one of the backwards compatibility features of the new PWM fan design is that its speed CAN be controlled by the older Voltage Control Mode, even though technically this is not quite ideal.

So, OP, that Deepcool FH-04 unit you noted is a SPLITTER the way I use the term. It has NO access to external power, and depends entirely on the mobo header for power. IF you are concerned that 0.9 A total for 3 fans is getting too close to the 1.0 A limit of a mobo header, then this is NOT the HUB you want. A basic HUB might look like a group of arms, like this one with 3 outputs

https://www.newegg.com/black-en-labs-11-15-cable-splitters/p/1W7-004Z-00039?Description=fan Hub&cm_re=fan_Hub-_-9SIACJF5497318-_-Product

This one has five outputs and looks like a small circuit board. You do NOT need to connect your CPU fan to the port labelled for that - it is just the only output that sends back to the host mobo header the speed signal of its fan.

https://www.newegg.com/p/1W7-005X-00071?Description=fan Hub&cm_re=fan_Hub-_-1W7-005X-00071-_-Product

If you want a closed box type with ports, here's an example, the Deepcool FH-10 with 10 fan ports and a SATA power connection.

https://www.newegg.com/p/N82E16811990016?Description=fan Hub&cm_re=fan_Hub-_-11-990-016-_-Product

Your two fans included with the Corsair Carbide 275R case are a different question. I cannot find a spec for exactly what fans those are, but I suspect them may be 3-pin models. Look closely at their fan connectors. Do the have three holes in them, or four? If THREE holes, then these are 3-pin fans that can ONLY be connected together to a header using a SPLITTER (like the FH-04 model you noted, or others), AND that header MUST be configured to use the DC Mode for control. IF the two case fans have FOUR holes in their connectors, then you CAN plug them into the SAME HUB you are going to use for your ThermalTake fans, and have them all share the same control signal from a single mobo header using PWM Mode. That works because the HUB does not pull its power from the header with its 1.0 A limit - the HUB get power from the PSU.
 
Jul 28, 2019
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The manual for that board says the headers are rated for 1A (12w). Just add up the amperage of all fans you want to connect to the header and make sure they add up to less than 1000mA
Hi thanks for replying my amperage for:

Thermaltake Riing 12 sync: 0.30 AMP x 3=0.90 AMP

Pre-installed fan: 0.38 AMP x 2 = 0.76 AMP

Cpu cooler, coolmaster ma610p: 0.37 AMP x 2 = 0.74 AMP

Just want to make sure this alright and correct?
 
Hi thanks for replying my amperage for:

Thermaltake Riing 12 sync: 0.30 AMP x 3=0.90 AMP

Pre-installed fan: 0.38 AMP x 2 = 0.76 AMP

Cpu cooler, coolmaster ma610p: 0.37 AMP x 2 = 0.74 AMP

Just want to make sure this alright and correct?
That would be OK if you attached them exactly like that using three splitters (one 3-way and two 2-way). All of the fans would then be thermally controlled by the motherboard, but note the tachometer numbers would also add up for each header (depends on the splitter) so any failed-fan alarms may not work.

In reality, the fans can only draw that much power while all simultaneously spinning up to immediate full blast. That should only happen if your computer was somehow already overheating before you switched it on, although some motherboards also do this on purpose during cold boots for dust-clearing. In any case that max load can only be momentary.
 
This is a fine example of why I complain about the way various makers use or misuse the terms. But I have to concede that the way I use the words is not decreed by anybody.

To me, a fan SPLITTER is the simple device that connects several fans in parallel to the signals from a host mobo fan header, and that's all it does. It has NO connection to any other power source, so the power for ALL of the fans on a SPLITTER must come from the fan header and is subject to that header's limit, normally 1.0 A max total. A fan HUB is a different device and can be identified by the fact that it has a third type of connection - one arm that MUST be plugged into a power output (either 4-pin Molex or SATA) from the PSU. That is the source of power for ALL of the fans connected to the Hub, and it draws NO power from the host header. It does collect the PWM signal from the header and distribute that to all of its fans, but that does not overload that header line. And it does return to the header the speed signal from ONE of its ports, just as a Splitter does. However, since the HUB merely distributes the PWM signal to its fans via Pin #4, and also a fixed +12 VDC power source on Pin #2 for all its fans, it can ONLY control the speed of 4-pin (PWM type) fans and ONLY if it gets the PWM signal from the host header. Thus a HUB can NOT control the speed of any 3-pin fan, no more than a PWM Mode mobo header can.

A 3-pin fan can ONLY be controlled for speed if its mobo header is using the older Voltage Control Mode in which changing the VOLTAGE on Pin #2 is the MODE of controlling speed. A 4-pin fan normally receives instead a fixed 12 VDC supply on Pin #2 and an additional PWM signal which is used inside the fan by a special chip to modify the current from that power source through the windings to effect control of fan speed. So the rule is (IF you use my way of labeling these two different devices) you can use a HUB only with a mobo header that is using PWM Mode to control, and ONLY if the fans are all of the 4-pin PWM type that has the special chip to use that signal. IF you are using 3-pin fans the mobo header can ONLY control their speeds if it is using the older Voltage Control Mode (aka DC Mode), and that means you can NOT use a HUB for this situation, you must use a SPLITTER instead. Let me say right here that I know of ONE Hub that does not follow this "rule". The Phanteks PWM Hub is different because it "converts" from the PWM system it MUST have from its host header and creates its own group of six 3-pin ports that DO use the older Voltage Control Mode and thus CAN control 3-pin fans. Also we should note that one of the backwards compatibility features of the new PWM fan design is that its speed CAN be controlled by the older Voltage Control Mode, even though technically this is not quite ideal.

So, OP, that Deepcool FH-04 unit you noted is a SPLITTER the way I use the term. It has NO access to external power, and depends entirely on the mobo header for power. IF you are concerned that 0.9 A total for 3 fans is getting too close to the 1.0 A limit of a mobo header, then this is NOT the HUB you want. A basic HUB might look like a group of arms, like this one with 3 outputs

https://www.newegg.com/black-en-labs-11-15-cable-splitters/p/1W7-004Z-00039?Description=fan Hub&cm_re=fan_Hub-_-9SIACJF5497318-_-Product

This one has five outputs and looks like a small circuit board. You do NOT need to connect your CPU fan to the port labelled for that - it is just the only output that sends back to the host mobo header the speed signal of its fan.

https://www.newegg.com/p/1W7-005X-00071?Description=fan Hub&cm_re=fan_Hub-_-1W7-005X-00071-_-Product

If you want a closed box type with ports, here's an example, the Deepcool FH-10 with 10 fan ports and a SATA power connection.

https://www.newegg.com/p/N82E16811990016?Description=fan Hub&cm_re=fan_Hub-_-11-990-016-_-Product

Your two fans included with the Corsair Carbide 275R case are a different question. I cannot find a spec for exactly what fans those are, but I suspect them may be 3-pin models. Look closely at their fan connectors. Do the have three holes in them, or four? If THREE holes, then these are 3-pin fans that can ONLY be connected together to a header using a SPLITTER (like the FH-04 model you noted, or others), AND that header MUST be configured to use the DC Mode for control. IF the two case fans have FOUR holes in their connectors, then you CAN plug them into the SAME HUB you are going to use for your ThermalTake fans, and have them all share the same control signal from a single mobo header using PWM Mode. That works because the HUB does not pull its power from the header with its 1.0 A limit - the HUB get power from the PSU.
 
Jul 28, 2019
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This is a fine example of why I complain about the way various makers use or misuse the terms. But I have to concede that the way I use the words is not decreed by anybody.

To me, a fan SPLITTER is the simple device that connects several fans in parallel to the signals from a host mobo fan header, and that's all it does. It has NO connection to any other power source, so the power for ALL of the fans on a SPLITTER must come from the fan header and is subject to that header's limit, normally 1.0 A max total. A fan HUB is a different device and can be identified by the fact that it has a third type of connection - one arm that MUST be plugged into a power output (either 4-pin Molex or SATA) from the PSU. That is the source of power for ALL of the fans connected to the Hub, and it draws NO power from the host header. It does collect the PWM signal from the header and distribute that to all of its fans, but that does not overload that header line. And it does return to the header the speed signal from ONE of its ports, just as a Splitter does. However, since the HUB merely distributes the PWM signal to its fans via Pin #4, and also a fixed +12 VDC power source on Pin #2 for all its fans, it can ONLY control the speed of 4-pin (PWM type) fans and ONLY if it gets the PWM signal from the host header. Thus a HUB can NOT control the speed of any 3-pin fan, no more than a PWM Mode mobo header can.

A 3-pin fan can ONLY be controlled for speed if its mobo header is using the older Voltage Control Mode in which changing the VOLTAGE on Pin #2 is the MODE of controlling speed. A 4-pin fan normally receives instead a fixed 12 VDC supply on Pin #2 and an additional PWM signal which is used inside the fan by a special chip to modify the current from that power source through the windings to effect control of fan speed. So the rule is (IF you use my way of labeling these two different devices) you can use a HUB only with a mobo header that is using PWM Mode to control, and ONLY if the fans are all of the 4-pin PWM type that has the special chip to use that signal. IF you are using 3-pin fans the mobo header can ONLY control their speeds if it is using the older Voltage Control Mode (aka DC Mode), and that means you can NOT use a HUB for this situation, you must use a SPLITTER instead. Let me say right here that I know of ONE Hub that does not follow this "rule". The Phanteks PWM Hub is different because it "converts" from the PWM system it MUST have from its host header and creates its own group of six 3-pin ports that DO use the older Voltage Control Mode and thus CAN control 3-pin fans. Also we should note that one of the backwards compatibility features of the new PWM fan design is that its speed CAN be controlled by the older Voltage Control Mode, even though technically this is not quite ideal.

So, OP, that Deepcool FH-04 unit you noted is a SPLITTER the way I use the term. It has NO access to external power, and depends entirely on the mobo header for power. IF you are concerned that 0.9 A total for 3 fans is getting too close to the 1.0 A limit of a mobo header, then this is NOT the HUB you want. A basic HUB might look like a group of arms, like this one with 3 outputs

https://www.newegg.com/black-en-labs-11-15-cable-splitters/p/1W7-004Z-00039?Description=fan Hub&cm_re=fan_Hub--9SIACJF5497318--Product

This one has five outputs and looks like a small circuit board. You do NOT need to connect your CPU fan to the port labelled for that - it is just the only output that sends back to the host mobo header the speed signal of its fan.

https://www.newegg.com/p/1W7-005X-00071?Description=fan Hub&cm_re=fan_Hub--1W7-005X-00071--Product

If you want a closed box type with ports, here's an example, the Deepcool FH-10 with 10 fan ports and a SATA power connection.

https://www.newegg.com/p/N82E16811990016?Description=fan Hub&cm_re=fan_Hub--11-990-016--Product

Your two fans included with the Corsair Carbide 275R case are a different question. I cannot find a spec for exactly what fans those are, but I suspect them may be 3-pin models. Look closely at their fan connectors. Do the have three holes in them, or four? If THREE holes, then these are 3-pin fans that can ONLY be connected together to a header using a SPLITTER (like the FH-04 model you noted, or others), AND that header MUST be configured to use the DC Mode for control. IF the two case fans have FOUR holes in their connectors, then you CAN plug them into the SAME HUB you are going to use for your ThermalTake fans, and have them all share the same control signal from a single mobo header using PWM Mode. That works because the HUB does not pull its power from the header with its 1.0 A limit - the HUB get power from the PSU.
thanks for this useful very detailed information i was confused about splitters, My Deepcool FH-04 having no external power to psu so this would be just a basic hub

By the way i am thinking of getting the first link HUB you mentioned, but i have a question could i get 2 x Black net jacket sleeved 12 inch Molex 4 pin to 3 x 4pin PWM fan power splitter hub adapter cable, and put one for CHA_FAN1 for the 3 fans and another for CHA_FAN2 because my front has two case fans? thanks for your help
 
You may still be a little confused by the labels on these things, and the way I use the terms. That FH-04 unit to me is just a SPLITTER that happens to be in a box-like module rather than a group of wire arms. It is the maker's other product, the FH-10 unit, that really is a HUB.

Your two case fans are THREE-pin units, I expect. Check their fan connectors - do they have THREE holes, or four? If they are 3-pin fans, then the ONLY way to connect them together is to use a SPLITTER that does NOT have a connecting arm to the PSU, and to plug that into a mobo fan header that you configure to use the older Voltage Control Mode (aka DC Mode). For that situation you need a simple SPLITTER like the FH-04 model OR one of the "group of wire arms" type, maybe like this

https://www.newegg.com/p/N82E16812423161?Description=Coboc fan splitter&cm_re=Coboc_fan_splitter-_-12-423-161-_-Product

That one has 12" arms, but a 6" model is available. It's a 4-pin design, but works just fine with 3-pin fans.

If the case fans are of the 3-pin type, then use a Splitter to connect to a mobo CHA_FAN header and be sure in BIOS Setup to configure that header to use the older DC Mode for control.

The first HUB link I cited and you chose IS the correct way to connect your three ThermalTake Riing fans (4-pin type) to a single mobo CHA_FAN header, and that one must be configured to use the newer PWM Mode.
 

digitalgriffin

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Paper Doc gave a very clear explanation with a lot of detail. I'm going to give you the TLDR:

1. Each fan you put on the motherboard consumes so many amps. If you have two fans that each consume 0.2 Amps, then you are pulling 0.4 Amps total. The power consumption is typically listed on the BACK of the fan hub or on website specs.

2. Most headers will handle up to 1 AMP. That means you can use a PASSIVE fan splitter like Paper Doc linked if the total of your fans is below 1 AMP. Passive splitters work well with both PWM fans (4 pin) and Variable Voltage (3 pin) fans.

3. If you are like me, and flooded your system with fans (nine-140mm fans) you would likely want to use a POWERED Splitter. However these work with 4 pin PWM headers only and 4 pin PWM fans only. The power comes from a SATA cable or a Molex cable. Only two pins are used from the motherboard (PWM control (pin 4) and RPM Sensor (pin 3))

https://www.amazon.com/XSPC-8-Way-PWM-Splitter-Black/dp/B07CH1958W?psc=1&SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-d-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B07CH1958W

Side note: I ordered a passive splitter before. They mistakenly hooked up all four pins on the cable to both fans. When you use a passive splitter, one fan header should have 3 wires instead of 4. This is normal as you only want one fan to report RPMs. If you have two fans reporting RPMs it will return an incorrect reading.
 
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Karadjgne

Titan
Herald
While I agree with paperdoc, it's only mostly. To me there's 3 distinct types of ways to gang multiple fans.
  1. Splitter. That's 1 header connection and multiple fan connections joined together by wires.
  2. Powered splitter is identical to #1 except it has a power lead included, usually Sata or molex.
  3. Hub. This is a pcb. Either standalone or shrouded in plastic. Contains circuitry, filters, step up/step down transformers or other various components. It's not a wire or series of wires, but a solid object that wires from power, input and outputs connect to. Can include fans, rgb, argb, strips, or any combination of those.
 
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You may still be a little confused by the labels on these things, and the way I use the terms. That FH-04 unit to me is just a SPLITTER that happens to be in a box-like module rather than a group of wire arms. It is the maker's other product, the FH-10 unit, that really is a HUB.

Your two case fans are THREE-pin units, I expect. Check their fan connectors - do they have THREE holes, or four? If they are 3-pin fans, then the ONLY way to connect them together is to use a SPLITTER that does NOT have a connecting arm to the PSU, and to plug that into a mobo fan header that you configure to use the older Voltage Control Mode (aka DC Mode). For that situation you need a simple SPLITTER like the FH-04 model OR one of the "group of wire arms" type, maybe like this

https://www.newegg.com/p/N82E16812423161?Description=Coboc fan splitter&cm_re=Coboc_fan_splitter--12-423-161--Product

That one has 12" arms, but a 6" model is available. It's a 4-pin design, but works just fine with 3-pin fans.

If the case fans are of the 3-pin type, then use a Splitter to connect to a mobo CHA_FAN header and be sure in BIOS Setup to configure that header to use the older DC Mode for control.

The first HUB link I cited and you chose IS the correct way to connect your three ThermalTake Riing fans (4-pin type) to a single mobo CHA_FAN header, and that one must be configured to use the newer PWM Mode.
Hi, i have just got another 120mm fan so now i have a total of 3 x 120mm fan (3 pin) and 3 x 120mm (4 pin) so now i should just need to buy 2 x of this

https://www.newegg.com/black-en-labs-11-15-cable-splitters/p/1W7-004Z-00039?Description=fan Hub&cm_re=fan_Hub-_-9SIACJF5497318-_-Product
 
Not quite right yet. Jaradjgne and I disagree a bit on the way to use the labels. I prefer to classify according to electrical function, and not on appearance. The items that karadjgne calls a "powered splitter" is really a HUB, in my opinion. And that is exactly what you have linked to above. If you look at it closely, it has one female connector that plugs into a mobo fan header, one male 4-pin Molex that plugs into a Molex power output from the PSU, and three male fan output connectors. The electrical connections work this way.
1. The cable to the mobo header connects to Ground (Pin #1), Speed signal return (Pin #3) for only ONE of its outputs as it should do, and to the PWM signal source on Pin #4. The cable to the Molex from the PSU provides both a fixed +12 VDC power supply and Ground. At each of the three outputs for fans, the fan receives the Ground and PWM signals from the mobo header (Ground also from the Molex connector) and the fixed +12 VDC power supply from the PSU. The fans draw NO power from the mobo header; all their power is from the PSU. ONE of the fan output connectors also sends back to the mobo header the speed signal from its fan. This makes ALL of the outputs from the device just like the output from a mobo header that uses only the new PWM Mode of speed control. That is, the motor receives Ground, +12 VDC (fixed), and PWM signals. The motor MUST have its own special chip inside that uses the PWM signal to modify current flow from the +12 VDC supply through the windings to adjust fan speed. That is, the fan used here MUST be of the new 4-pin PWM type. NO 3-pin fan can have its speed controlled in this way, so you can NOT use this device with any 3-pin fan.

OP, this device IS what you need for use with your group of 4-pin fans, and I call it a HUB. BUT for your group of THREE-pin fans you must get a SPLITTER that does NOT have any connection to a PSU output for power. A SPLITTER depends solely on the power on Pin #2 of the mobo header. As long as that header is configured to use the older DC Mode for control, that power supply line will provide a VARYING voltage (not a fixed +12 VDC) to control the fan motor speed.
 
Reactions: puria101
Jul 28, 2019
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Not quite right yet. Jaradjgne and I disagree a bit on the way to use the labels. I prefer to classify according to electrical function, and not on appearance. The items that karadjgne calls a "powered splitter" is really a HUB, in my opinion. And that is exactly what you have linked to above. If you look at it closely, it has one female connector that plugs into a mobo fan header, one male 4-pin Molex that plugs into a Molex power output from the PSU, and three male fan output connectors. The electrical connections work this way.
1. The cable to the mobo header connects to Ground (Pin #1), Speed signal return (Pin #3) for only ONE of its outputs as it should do, and to the PWM signal source on Pin #4. The cable to the Molex from the PSU provides both a fixed +12 VDC power supply and Ground. At each of the three outputs for fans, the fan receives the Ground and PWM signals from the mobo header (Ground also from the Molex connector) and the fixed +12 VDC power supply from the PSU. The fans draw NO power from the mobo header; all their power is from the PSU. ONE of the fan output connectors also sends back to the mobo header the speed signal from its fan. This makes ALL of the outputs from the device just like the output from a mobo header that uses only the new PWM Mode of speed control. That is, the motor receives Ground, +12 VDC (fixed), and PWM signals. The motor MUST have its own special chip inside that uses the PWM signal to modify current flow from the +12 VDC supply through the windings to adjust fan speed. That is, the fan used here MUST be of the new 4-pin PWM type. NO 3-pin fan can have its speed controlled in this way, so you can NOT use this device with any 3-pin fan.

OP, this device IS what you need for use with your group of 4-pin fans, and I call it a HUB. BUT for your group of THREE-pin fans you must get a SPLITTER that does NOT have any connection to a PSU output for power. A SPLITTER depends solely on the power on Pin #2 of the mobo header. As long as that header is configured to use the older DC Mode for control, that power supply line will provide a VARYING voltage (not a fixed +12 VDC) to control the fan motor speed.
Thank you alot i think i may have got it right
 

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