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2 pin fan splitters

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  • Amazon
  • Fan
  • Components
  • Motherboards
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October 1, 2014 5:57:53 PM

I recently ordered a 4 way fan splitter from amazon. I noticed that 3 of the 4 splitters only has 2 pins instead of 3. I am just wondering will the motherboard still be able to control the speed of these fans if the splitter only has 2 pins or will it run at 100% all the time?

More about : pin fan splitters

a c 519 V Motherboard
October 1, 2014 7:40:10 PM

Can you link us to the exact splitter you ordered? It will depend on what pins were missing and how it was wired.

But I suspect from your description that the missing pins on the other three connectors are the tach feedback. That is normal. The MB BIOS wants to see only a single feedback for calibration. If the fans are all identical, they will all run at the same speed anyway. The one fan that is plugged into the 3 pin connector will be the 'master' so to speak. The other 2 wires/pins are +12V and ground.

But I caution you about connecting 4 fans to a single MB fan header. Most headers are only good for ~1 amp. Most fans are at least 1/4 amp. But that is running current. Locked rotor (starting) current can go several times higher.
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October 1, 2014 8:09:41 PM

clutchc said:
Can you link us to the exact splitter you ordered? It will depend on what pins were missing and how it was wired.

But I suspect from your description that the missing pins on the other three connectors are the tach feedback. That is normal. The MB BIOS wants to see only a single feedback for calibration. If the fans are all identical, they will all run at the same speed anyway. The one fan that is plugged into the 3 pin connector will be the 'master' so to speak. The other 2 wires/pins are +12V and ground.

But I caution you about connecting 4 fans to a single MB fan header. Most headers are only good for ~1 amp. Most fans are at least 1/4 amp. But that is running current. Locked rotor (starting) current can go several times higher.

http://www.amazon.com/gp/product/B00DYQSZ68/ref=oh_aui_... these were the ones I ordered
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a c 519 V Motherboard
October 2, 2014 10:51:29 AM

Yes, the missing pin in the 3 "slave" connectors are the tach feedback as I outlined above. That is the proper way to run multiple fans off of a single header. But bare in mind the disclaimer I mentioned above. No more than 2 fans per MB sys fan header and all fans must be identical. What MB are you using and which fans?
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October 2, 2014 11:12:01 AM

clutchc said:
Yes, the missing pin in the 3 "slave" connectors are the tach feedback as I outlined above. That is the proper way to run multiple fans off of a single header. But bare in mind the disclaimer I mentioned above. No more than 2 fans per MB sys fan header and all fans must be identical. What MB are you using and which fans?


I am using the msi z87 g45 mobo and use the yate loons ds12sl-12 120mm fans. So as long as I connect one of the fans to the 3 pin connector, the other fans should follow the same speed? Also would connecting 3 fans to one header be fine or is that too dangerous for the mobo?
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a c 519 V Motherboard
October 2, 2014 3:04:17 PM

If these are your fans: http://www.acousticpc.com/yate_loon_d12sl-12_120mm_quie...
...they draw 0.3 amps running current. 3 of those on one header would total .9 amp. But where the problem might come in, is starting current. It can be double the running current for a fraction of a second. Personally, I would not run more than 2 of those fans on a single header. You risk burning out the MB's fan control.

If you want to control your fans, there are better ways than ganging them up on a MB fan header. Use a fan controller.
Besides. your MB's fan headers are 4 pin. The MB's fan controller may be PWM* only, meaning a 3 wire fan will always run at full RPM no matter what the setting in BIOS is. Give it a try with one fan on each header to test it out. If it is like every other board I've built with that only had 4 pin sys fan headers, you won't be able to control the 3 pin fan's speed.

PWM = Pulse Width Modulation
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October 2, 2014 3:28:19 PM

clutchc said:
If these are your fans: http://www.acousticpc.com/yate_loon_d12sl-12_120mm_quie...
...they draw 0.3 amps running current. 3 of those on one header would total .9 amp. But where the problem might come in, is starting current. It can be double the running current for a fraction of a second. Personally, I would not run more than 2 of those fans on a single header. You risk burning out the MB's fan control.

If you want to control your fans, there are better ways than ganging them up on a MB fan header. Use a fan controller.
Besides. your MB's fan headers are 4 pin. The MB's fan controller may be PWM* only, meaning a 3 wire fan will always run at full RPM no matter what the setting in BIOS is. Give it a try with one fan on each header to test it out. If it is like every other board I've built with that only had 4 pin sys fan headers, you won't be able to control the 3 pin fan's speed.

PWM = Pulse Width Modulation

do you think these would be a better option? http://www.amazon.com/Splitter-Molex-headers-CONNECT-MU... they plug in directly to the psu. I am not sure if the fan speeds are controlled by the mobo though. Thank you for the consistent replies. I dont really know a lot about these fan configurations.
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a c 519 V Motherboard
October 2, 2014 3:50:37 PM

Those will be fine, but you won't have any speed control over the fans that way either. They will be receiving a full +12V DC all the time. As a result they will run at full speed all the time.

3-wire fans have their speed controlled by varying the DC voltage (5VDC to 12VDC). PWM fans have their speed controlled by pulsing the DV voltage on and off rapidly (constant 12VDC).

If you have the room, one of these will control the fan speed of 3 wire fans: http://www.newegg.com/Product/ProductList.aspx?Submit=E...
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October 2, 2014 4:28:56 PM

clutchc said:
Those will be fine, but you won't have any speed control over the fans that way either. They will be receiving a full +12V DC all the time. As a result they will run at full speed all the time.

3-wire fans have their speed controlled by varying the DC voltage (5VDC to 12VDC). PWM fans have their speed controlled by pulsing the DV voltage on and off rapidly (constant 12VDC).

If you have the room, one of these will control the fan speed of 3 wire fans: http://www.newegg.com/Product/ProductList.aspx?Submit=E...


Im not really looking to control the speeds of the fans myself. I'd like them to be controlled by the motherboard so that they dont run 100% all the time. Wouldn't the connector to the right of the molex connector on this item http://www.amazon.com/Splitter-Molex-headers-CONNECT-MU... allow the mobo to control rest of the fans?
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a c 519 V Motherboard
October 2, 2014 4:58:32 PM

Only if you plug 4-pin (PWM) fans into the other three connectors. As the title say, "CONNECT MULTIPLE PWM FANS". Your 3 fans are not PWM fans. They are simple 2 wire fans with a 3rd wire for tach feedback.

Have you even tried one fan on the header yet to see if you can control it with the MB BIOS?
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October 2, 2014 8:40:43 PM

clutchc said:
Only if you plug 4-pin (PWM) fans into the other three connectors. As the title say, "CONNECT MULTIPLE PWM FANS". Your 3 fans are not PWM fans. They are simple 2 wire fans with a 3rd wire for tach feedback.

Have you even tried one fan on the header yet to see if you can control it with the MB BIOS?


I am thinking about just connecting my remaining fans directly to the psu and running them at 100%. Are theyre any negatives to having your fans running at 100% besides maybe a little more power bill?
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a b V Motherboard
October 2, 2014 8:55:15 PM

Noise
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a c 519 V Motherboard
October 3, 2014 12:02:45 PM

0.3 of an amp at +12V (3.6W) is almost impossible to detect on a modern electric bill. 3 fans x 3.6W = less than 11W. About the same as a common nite lite. Slowing them down to a lower speed and wattage would maybe make it half that. Like Karadjgne says, noise is the only thing you may object to.

You could use something like this to slow the fans down on the cheap: http://www.moddiy.com/products/4%252dPin-IDE-Power-Conn...
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a b V Motherboard
October 3, 2014 5:09:05 PM

The MSI z87-g45 has 2x cpu and 3x sys fan headers. Just how many fans are you running to have a need for a 4-way splitter since realistically you could run cpu and 4x sys fans if you slapped rear exhaust on cpu_aux?
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a c 519 V Motherboard
October 3, 2014 5:57:00 PM

The OP has 3 wire fans and the board has 4 wire (PWM) sys headers. I doubt the board's speed control will work with 3 wire fans. They will probably run at full speed all the time. But I asked him if he ever tried it to see if that was the case. He never replied.
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a b V Motherboard
October 3, 2014 7:51:33 PM

I sorta had that with my Asus p8z77, the cpu was 4-pin pwm only, but the 2 sys are 3-pin. My current msi m-power z77 is all 4-pin but will control either. Of course my original h55 fan was 3-pin, drove me nuts till I got a pwm Noctua.
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a c 519 V Motherboard
October 3, 2014 7:55:36 PM

Lately, I've been buying PWM case fans myself. Makes life easier since most new boards are using 4 pin sys fan headers now.
(besides, I hate Molex connectors)
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a b V Motherboard
October 3, 2014 9:21:33 PM

Me too, but it would be an engineering marvel if someone could figure out how to get the amperage a molex will carry into a Sata connector.
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a c 519 V Motherboard
October 4, 2014 10:11:45 AM

I would be happy if the standards people would just do away with the old Molex design and replace it with an easier to use connector.

9 times out 10 I can't get all 4 loose wobbly pins to line up with the 4 loose wobbly holes in the mating plug. Either that, or I finally get it plugged together only to find one of the pins has backed out of its connector. If I couldn't design a connector better than that, I'd turn in my engineering license.
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a b V Motherboard
October 5, 2014 4:57:15 PM

Haha.
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