CPU fan insane overload under idle state

Feb 28, 2018
Just as title states my cpu fan went insane recently. Just turned on my PC today and the CPU fan noise gradually raised from silent to extremely noisy in few minutes. However CPU usage is around 0-2%.

Before you post that it's not CPU fan, I'd like to let you know that my PC doesn't have any dedicated GPU or anything else with a fan except CPU.

This whole crap started today and it's driving me crazy, the noise is unbearable.

CPU I'm using: i3-6100

I even scanned for virus with crap anti-virus software "windows defender" however none were found.
Feb 28, 2018

I don't update my windows, or at least haven't in a long time.

UPDATE: the overload and noise issue disappeared after several hours. I've no idea what has caused it, but I'll check next morning again if this repeats.


Mar 3, 2017
Although this sounds like it's OS or hardware related, it did remind me of cryptojacking. Compromised websites can hijack a browser tab/process to use your CPU, mining cryptocurrency without your knowledge. This would generally cause a CPU spike (which you didn't observe, but which would be accompanied by increased heat and fan speed). Just something to watch out for :)

Another thing to check -- your BIOS. See if there are any updates available there if the issue comes up again.


Jan 4, 2018
This has happened to me a lot too. In my opinion there are two reason that it happens:

1. Other components in the computer are getting hotter and the CPU fan is trying to get the heat out;

2. The CPU fan is getting too much voltage.

The first and the second thing happened to me. The second thing happened when I opened my case, disconnected the CPU fan and cleaned all of the dust from it. When I plugged it back, the CPU fan started spinning very fast and POST during boot told me: "CPU fan overload". Then I just opened up my case, disconnected the fan and connected it again and everything worked fine. If the fan keeps spinning very fast, probably the second reason I mentioned occured. However there's probably more reasons out there that it occurs, but those were the ones I had. However if you don't know how to unplug your CPU fan, just do this (You can probably only do this with desktop PCs (I think it is possible to do it with a laptop too, but I dont recommend it (If you have a laptop, better hand it out to someone that is good with these kinds of things and he'll figure what's the problem))):

1. Disconnect the PC from any kind of power source.
2. Open up the case.
3. Check where the CPU fan is (If you can't disconnect it by removing the heat sink, just leave it and contact
someone that can do it for you and put the thermal paste onto the CPU again or maybe buy the thermal
paste yourself and then do it yourself (Thermal paste costs about 5-10 dollars) (If you don't know how to put
the thermal paste onto the CPU again, check this link: https://www.wikihow.com/Apply-Thermal-Paste)
4. Once you've found the CPU fan, disconnect it, connect it again and check if it works.

If it still doesn't work, try going into your BIOS and checking if maybe the CPU fan is set to spin at its fastest rate. BIOS could of automatically set it to spin at its fastest rate during it was idle. If it's still not the case, try contacting someone that is good with these kinds of things and he'll figure it out.

I hope this helps in any way.