Why CPU FAN doesn't work?

[MCyra]

I have got S1200SPS motherboard and Noctua NF-A15 PWM Fan. When I was checking BMC I discovered that RPM sensor is not reading speed of that fan but the fan was working. I hot swapped the fan to another connector - SYSFAN2 and it stopped spinning. When I connected fan back to CPUFAN it still was not spinning. I reset SDR multiple times with different options but fan still doesn't work. I bought new one, exactly the same and the new one behaves as the old one. I found that both fans work when i connect them using only 3 pins instead of 4.

Fans are working fine when they are connected to SYSFAN4 connector, but doesn't work when connected to CPUFAN, SYSFAN2, SYSFAN3.

Does it mean I might have damaged my motherboard ? How can I fix it ?

[AlHill]

You have a server board. You need to post in this forum:

https://forums.intel.com/s/topic/0TO0P00000018NYWAY/servers

Doc

[MCyra]

I just did that. Thanks for help!

[n_scott_pearson]

First of all, you should never hot swap fans; I have seen this kill fan headers. Secondly, if this board has support for automatic fan type (3-wire vs 4-wire) detection, this is done at board power on.

...S