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3-pin into Mobo; can't control fan speed?

Last response: in Overclocking
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June 21, 2012 4:06:18 PM

Hi everyone, got a minor problem - can't control any of my fan's speeds, and I've got 2/3 of them plugged directly into my mobo by 3 and 4 pin headers.

SpeedFan won't modify any of the speeds, whatsoever. I have a Biostar tp35d2-a7 mobo if it's any consolation...

Any ideas?

Thanks in advance!

Forgot to add, I've enabled Smartfan in BIOS...still won't let me change speed of anything.
The speeds fluctuate 10% give or take,
742-862RPM on Fan1
2450-2500RPM on Fan2 (THE ONE I WANT TO QUIET!!)
1980-2020RPM on Fan3

I *can* control the fan on my GPU though, effortlessly.

Specs are Intel Q8400 Core 2 Quad @ 3.3GHz
Idle temps 31c on each core, roughly
ATI Radeon 5700 400/900 39c idle/52c load

the Fan#2 is my side case fan, and I just want to quiet the bugger down, maybe around 1100 rpm would be nice...

Yet another edit: I've found this Googling my mobo+fan
"Fan speed control, but only on the D2
Both boards offer automatic fan speed control for the CPU cooler, but curiously, only the D2's BIOS gives you control over temperature thresholds and actual fan speeds. On the D3, fan speed control is nowhere to be found in the BIOS, limiting users to the default configuration. One would hope, given similarities elsewhere in the BIOS, that additional fan control functionality could be incorporated into future D3 BIOS releases."

Acompanied by this picture, pretty sure you guys don't have html tags enabled...so here's a direct link
http://techreport.com/r.x/biostar-p35s/bios-fan.jpg

Basically says:
PWM Duty Off(*c) [value]
PWM Duty Start(*c) [value]
Start PWM Value [value]
Smart FAN Slope [value]

No idea what any of that means though, ideas?
a b K Overclocking
June 21, 2012 4:22:11 PM

three pins cant do fan speed it the 4 pin the lets the mb use pulse with modulation. (pwm). also you need to have fans that have 4 pins and are made to speed up and slow down. if all the headers on your mb are three pins the cheaper way is to put a resitor cable on the fan you want to slow down. there call 5v/7/12v fan cables. you be able to cut the 12v down and slow the fan. or you have to by a fan controller that you can adjust the voltage to the three pin fans you have. if you have a few four pin headers then i would pick up some long cables to reach some new 4 pins fan.
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June 21, 2012 4:26:25 PM

Just a sec, rebooting and making sure I'm not absolutely crazy...I didn't know that 3 pins weren't PWM - thank you for telling me what it was, though.


Brb in a few minutes.

Edit: So, as it turns out you're absolutely right - the fans I'm wanting to slow down are 3-pins, but there's also a molex connection...but iirc, if I use molex I'm still in the same situation, max RPMs - what avenues can I take to slow these down?

I've got to splice out the red and yellow wires, to provide less voltage, right?

Alright, figured it out - did a 5v mod on my fan since my molex connector only had black/yellow wires, put the yellow to the red wire on my female end - works awesome, and quiet, just how I need it.
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