2x 3-pin fans in 1 system fan header?

PILLAGER · Feb 2, 2014

hello ive taken the stock fan and plastic case off my 7870 and put 2x 92mm fans on the heatsink http://www.quietpc.com/ac-arctic-f9-pwm and I wanted know if I can somehow power both fans off the system fan header because there is only 1 on the board so that I can have a profile which will auto adjust the fan speed. this is the board http://www.gigabyte.com/products/product-page.aspx?pid=3583#sp

Jameson Clark · Feb 2, 2014

You can get fan header splitters

clutchc · Feb 2, 2014

Running 2 x 4 pin Pulse Width Modulated fans from one 3 pin header may not be very accurate. The RPM feed back from two +12V DC motors sending parallel signals simultaneously may not be interpreted correctly by the firmware on the MB.

PILLAGER · Feb 2, 2014

clutchc :

yeah I found a thread where they said cut one of the yellow cables (I think that is what tells rpm) but my main concern is it powering 2 fans from the one header

clutchc · Feb 2, 2014

PILLAGER :

Most MB fan headers are rated at 1 amp. Just be sure the current rating per fan puts that within specs.
On PWM fans, you can't assume it is the yellow wire. But it will always be the 3rd pin: http://savedonthe.net/image/986/pinout.png

PILLAGER · Feb 2, 2014

clutchc :

PILLAGER :

Most MB fan headers are rated at 1 amp. Just be sure the current rating per fan puts that within specs.
On PWM fans, you can't assume it is the yellow wire. But it will always be the 3rd pin: http://savedonthe.net/image/986/pinout.png

when I look at pics of these arctic cooling f9 pwm fans it shows 3pin connector is that wrong? if its pwm it must be 4?

PILLAGER · Feb 2, 2014

Current / Voltage

0.14 A / 12 V (F9)
0.15 A / 12 V (F9 PWM)
0.16 A / 12 V (F9 TC)

so running 2 of those is under 1 amp so it should be ok shouldn't it

PILLAGER · Feb 2, 2014

Operation Requirements

Motherboard: 12V power
PWM control signal (F9 PWM only)
3-pin socket

PILLAGER · Feb 2, 2014

actually ive seen someone unboxing 1 on youtube and they are 4pin but the system chassis fan header is only 3pin so this means it wont be able to control speed?

clutchc · Feb 2, 2014

PILLAGER :

It won't be able to control the speed by pulse width modulation. However, if the MB BIOS has the ability to ALSO control speed by variable DC voltage, it can. But very few MBs that use PWM 4 pin headers have that.
1) Have you checked your MB manual to see what (if any) fan speed control is possible?
2) And why would you want the MB's fan header speed control to set the speed for the gfx card fans?

clutchc · Feb 2, 2014

PILLAGER :

clutchc :

when I look at pics of these arctic cooling f9 pwm fans it shows 3pin connector is that wrong? if its pwm it must be 4?

I was just going by the link you posted at the top. The fans are PWM according to the page info.

PILLAGER · Feb 2, 2014

clutchc :

well this is my cpu fan http://www.arctic.ac/eu_en/products/cooling/cpu/freezer-7-64-pro.html and the bios controls the speed of that

well I thought I could have a profile in speedfan for the gpu fans but if its not pwm that wouldn't work would it? so what do you suggest I do, maybe I should just get one of those fan controller bays

clutchc · Feb 2, 2014

CPU fan? I thought you were talking about your gfx card?

PILLAGER · Feb 2, 2014

clutchc :

yeh I was telling you that the cpu fan header has pwm 4pin but the chassis is only 3

PILLAGER · Feb 2, 2014

another thing I might be able to do is put them on the 4pin on the graphics card but would it supply enough power. its a vtx3d 7870 2gb x edition

clutchc · Feb 2, 2014

PILLAGER :

Well, since you already bought the fans and did the work, might as well test it out. I wouldn't get my hopes up tho.

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