3 pin CPU fan on 4 pin motherboard headers

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oddlycalm

Limp Gawd
Joined
Jul 28, 2004
Messages
142
I'm getting ready to install a XP-90 on an Intel board with a 4 pin CPU header. The fan is a Panaflo BX with Rpm feedback. I'd like to have the fan speed controlled automatically by the chipset. Intel says that 3 pin connections on 4 pin headers prevents automatic fan control. True? If so, are their workarounds? The OEM sink/fan sucks. It doesn't do a good job of cooling although it makes plenty of noise when the system is under load.

I'm assuming fan control works with a 3 pin fan connection and a 3 pin board header because I'm doing that now with an existing system. The Adda case fans are connected to the board and report Rpm to the Desktop Control Center utility which controls their speed as well.

oc
 
Update: After some searching I have located some fans with 4 pin motherboard connectors that are capable of PWM (pulse width modulatio) speed control. Seems incredible to me that so may people would be adding heat sinks with fans having 3 pin connectors and running them at a constant speed.

oc
 
FWIW, I don't think I have an answer, but I might have some info to help clarify this for you. I'm in a slightly different situation- I'm trying to find out if a fan on a radiator for a water-cooled setup could be controlled by the CPU fan control on the motherboard. I did notice on my motherboard docs that the cpu fan controller is a 4-pin. The difference between it and the other 3-pin fan controller connections that the motherboard has is that there's a 'control' line present. Maybe this is what Intel meant- that the fan has to have the capability of using that control line, which the 3-pin fans wouldn't be able to?
 
lamarth said:
FWIW, I don't think I have an answer, but I might have some info to help clarify this for you. I'm in a slightly different situation- I'm trying to find out if a fan on a radiator for a water-cooled setup could be controlled by the CPU fan control on the motherboard. I did notice on my motherboard docs that the cpu fan controller is a 4-pin. The difference between it and the other 3-pin fan controller connections that the motherboard has is that there's a 'control' line present. Maybe this is what Intel meant- that the fan has to have the capability of using that control line, which the 3-pin fans wouldn't be able to?
Click to expand...



Then the 4 pin fans have 2 control lines?
 
GlobalFear said:
Then the 4 pin fans have 2 control lines?
Click to expand...
According to the manual (which is shown in a diagram but I'll just list the pin functions):

For 4-pin there is GND, +12V, RPM, CONTROL

For 3-pin there is GND, +12V, RPM
 
RPM is a sensor line. That's how the computer reads the RPMs. Only one control line for a 4 pin fan.
 
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