How many fans motherboard can take

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urpokekkonen

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Oct 6, 2014
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SO i have case with 5 4pin pwm fans and my mobo has only 3 4pin fan headers so is it safe to connect one fan alone to one header and 2 fans to one header with y splitter and last 2 fans to last header? Will it damage my mobo? It is Asus M5A97 Evo r2, and i have heard that one fan header can take up to 1 amper and one fan uses 0.3 +-10% amps, so technically one header would take 0.6+-% amps? And if this would work can someone link y 4pin pwm fan splitter?
I hope you understood
 
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urpokekkonen

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Oct 6, 2014
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IS this 100 sure? I dont wanna destroy my computer. And does they perform normally or do they split the powers? And why does one header have 1 pin less(see this link http://www.jimms.fi/tuote/AK-CBFA04-15)?
 
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geofelt

geofelt

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Oct 9, 2006
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The problem with splitting fan headers is that you lose the ability to control the speed of one fan via motherboard dynamic control.
The speed sensing wires will conflict unless you cut one of them.
You might just as well attach those fans to the psu where they will run at full speed.
Or, you can connect the fans to the psu via a manual speed controller.
 
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geofelt

geofelt

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Yes, the fans will spin at full speed.
If you cut one of the speed sensing wires(normally, the yellow one) only one fan will give speed sense to the motherboard.
That may be ok since for three pin fans, the motherboard controls speed via voltage output to the header.
I would not worry about overload with two fans per header so long as they are not high amperage high rpm fans.

If you directly attach some fans to the psu, a simple zalman fanmate speed controller is perhaps. 5€
 
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geofelt

geofelt

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Are your fans pwm type? Ot the normal case 3 pin type?
PWM 4 pin is normally only used for the cpu where the motherboard controls the speed by pulse width modulation(PWM) and not by voltage control.

 
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Colin Lee

Colin Lee

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Mar 16, 2013
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The missing pin is the fan RPM feedback for the motherboard, if they both had 3 pins connected the signals could conflict.
http://www.amazon.co.uk/Akasa-AK-CB002-PWM-splitter-smart/dp/B001J2YRUC/ref=sr_1_2?ie=UTF8&qid=1335461868&sr=8-2 and http://www.amazon.co.uk/Akasa-AK-CBFA04-15-Splitter-Cable-Fans/dp/B005FWXWPS/ref=pd_bxgy_computers_text_z are similar except for the fact that 1 accepts up to 3 fans and is powered from the PSU directly since there is a limit to the amperage that the motherboard can supply to each header.
The motherboard would control the speed of all the connected fans (whether 3 or 4 pins, since both work in these headers) but would just return the speed of the fan plugged into the socket with all 4 pins connected.
 
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sora

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Oct 30, 2013
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You do know this thread is a month old, right?
 
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Colin Lee

Colin Lee

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Yes, I was aware of that, but they may still be looking for answers. I only came across it because I was looking for some information myself.

Edit :- and I've just realised I should have said " if they both had 4 pins connected the signals could conflict".
Whoops.
 
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