Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have an MSI 970A-G43 motherboard and I have two Rosewill RFX-120 fans connected to the sysfan1 and sysfan2 connectors in the motherboard. The fan connected to the sysfan2 port is not being detected by the motherboard although it is receiving power since it is spinning. The fan connected to sysfan1 is being recognized by the motherboard and is labeled as "system fan 1" by the msi's software "control center". I also used the app "CPUID Hardware Monitor" to make sure that the problem wasn't just with msi's app. Here is a screenshot of both apps.(click on the image to see in full size). In the picture, only two fans' RPM is being detected(CPU fan and the one in sysfan1). The fan connected to sysfan2 is seen as having an RPM of 0 even though it is rotating.

I also used a fan speed control app to confirm that the fan being monitored was the one in sysfan1 connector. I used the app to stop the fan that was being recognized as system fan and indeed it was the fan connected to sysfan1 to that was brought to a stop. This also means that the sysfan1 and sysfan2 connectors are not synchronized or meant to be detected together as one fan.

The only difference in the the sysfan1 and sysfan2 connectors is that sysfan1 has 4 pins and sysfan2 has 3 pins. However, both fans are 3-pin fans meaning that the additional pin in sysfan1 is not being used and thus should not make a difference.

share|improve this question
    
If it only has 3 pins then what you want is not possible. In order to control the fan the header must have 4 pins. –  Ramhound Jun 26 '13 at 19:36
    
Actually, it is. One of the 3-pin fans is controlled. The other 3 pin fan is not being monitored. Also, they are both the same exact model of fans. The following link explains how it is possible. superuser.com/questions/580112/… –  Jorge24 Jun 26 '13 at 20:15
add comment

1 Answer

up vote 1 down vote accepted

The only difference in the the sysfan1 and sysfan2 connectors is that sysfan2 has 4 pins and sysfan1 has 3 pins. However, both fans are 3-pin fans meaning that the additional pin in sysfan2 is not being used and thus should not make a difference.

Your assumption is incorrect. You cannot plug a 3 pin connector into the first or last 3 pins of a 4 pin receiver, it will not work on all paths. Frankly you are lucky as it seems that you are most likely receiving power to the fan because of one of the middle pins.


UPDATE

It turns out your motherboards system fan 2 does not have a sensor pin as per their online manual. Unfortunately this means you will not be able to monitor speeds from that connector.

System Fans

share|improve this answer
    
Actually, the fan plugged in into the 4 pin receiver is the one that can be monitored by the motherboard. The one which is not being recognized is the one plugged into the 3 pin receiver. –  Jorge24 Jun 26 '13 at 20:02
    
The 3pin-fan-into-a-4pin-receiver question has already been answered here. superuser.com/questions/580112/… –  Jorge24 Jun 26 '13 at 20:05
1  
Hmm, well I learned something. My experience with trying that has always failed. The only thing I can think of then is that your input head might be damaged. If you swap your fans between sysfan1 and sysfan2 does sysfan1 all of a sudden have RPM data? –  Jason Bristol Jun 26 '13 at 20:10
    
i'm sorry i made a mistake(i wrote sysfan1 where i should have written sysfan2 and vice versa. I just edited it in the question). I just unplugged the fan from sysfan2 and plugged it into sysfan1 and it IS sending RPM data which is being monitored by msi's app. My only guess is that even though sysfan2 has 3 pin, it is not able to receive RPM data. –  Jorge24 Jun 26 '13 at 20:27
1  
Have you looked in your BIOS settings? I know with ASUS motherboards I can actually set if a fan reports its RPM or not. –  Jason Bristol Jun 26 '13 at 20:31
show 2 more comments

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.