Question CPU Fan struggles to spin

[undeadAtom]

Hello. I have a ASUS H81M-K and i5 4460

Recently, out of blue, I have noticed my CPU Fan stopped spinning when doing normal tasks on Windows. I don't know what could be the cause since I haven't changed anything in BIOS. It is important to note that the fan struggles to spin, after let's say 30 minutes, it completely spins normally then again stops and struggles.

Things I tried

1. I checked in BIOS the fan speed and it's set to auto, it says my fan is spinning at 1100RPM then changes to 'Undetected'. Seems like my fan loses signal with the mobo?
2. Swapped RAM, I researched across other forums and for others worked.

and most importantly, 3: If I remove CMOS Battery which forcefully resets the BIOS settings, the cooler starts spinning normally for 45-60 minutes then it again stops and starts to struggle spinning.

Any ideas what could be the possible cause? I thought my mobo was faulty but since the cooler works normally after I take out the cmos, I believe either it's fan's problem or something software related.

 

[punkncat]

Not unusual for fans to fail over time, and that one is pretty old. Aside from that, you could have a header going bad or possibly an issue with the power supply.

I think the first thing I would try would be to consider another CPU fan. Used or used "not used" stock Intel coolers go for nearly nothing.