[SOLVED] When I start my PC the top fan in my case spins with 100%

inowaterpolo

Commendable
Sep 13, 2018
3
0
1,510
0
Every time I turn on my PC the top fan starts spinning like crazy and making a loud sound and after like 5 minutes the rpm goes to normal again. This was not an issue before. I don't know why it's doing this. I didn't change something in bios. Does someone mabye know how to fix this? Thank you
 

Paperdoc

Glorious
Ambassador
You may not be observing a fast fan. Just a NOISY fan.

Fan bearings wear as they are used and get older. This increases the clearance between the fan shaft and the bore in the bearing sleeve. Once that clearance gets too large, this is what happens.

When you first start up a COLD system the fan makes a lot of noise because the shaft is "rattling around" in the sleeve. But as the bearings heat up from friction the shaft expands more than the sleeve, and the clearance gets narrower, until the noise stops. If you shut down and re-start right away with the fan still warmed up, you get no noise. But shut down for a long time to let it cool off, and the same story happens again. Over a long time, the length of the initial noise gets longer, until it always is noisy. After that the fan will simply seize up and not work at all.

The solution is to replace the fan. You cannot repair it. If this is a new thing and the initial noise is less than 5 minutes, it is not an emergency. But it WILL get worse, so plan to do the replacement some time.
 

Lutfij

Titan
Moderator
Welcome to the forums, newcomer!

What is the make and model of the top mounted fan and how is it connected to your system? If it's plugged in to the motherboard via a 3 or 4 pin header, check and see if the issue persists while in BIOS. Are you sure you've narrowed the noise to that one top fan? You're sure it's not the CPU cooler? Sorry I'm assuming here, you didn't mention your full system's specs which is why I'm asking around.
 

inowaterpolo

Commendable
Sep 13, 2018
3
0
1,510
0
Welcome to the forums, newcomer!

What is the make and model of the top mounted fan and how is it connected to your system? If it's plugged in to the motherboard via a 3 or 4 pin header, check and see if the issue persists while in BIOS. Are you sure you've narrowed the noise to that one top fan? You're sure it's not the CPU cooler? Sorry I'm assuming here, you didn't mention your full system's specs which is why I'm asking around.
Thank you for the warm welcome!

The top mounted fan is the NZXT Aer F 120 mm fan and it's connected with a 4 pin header in the motherboard. I'm positive its the top mounted case fan because I can feel the vibrations of the top fan while the back fan doesn't nearly make the same noice and vibrations. I also went into the BIOS and turned on the 'smart fan mode' and it was fixed for a couple start ups. But unfortunately its back to 100% speed everytime when I start my PC.
 

Paperdoc

Glorious
Ambassador
You may not be observing a fast fan. Just a NOISY fan.

Fan bearings wear as they are used and get older. This increases the clearance between the fan shaft and the bore in the bearing sleeve. Once that clearance gets too large, this is what happens.

When you first start up a COLD system the fan makes a lot of noise because the shaft is "rattling around" in the sleeve. But as the bearings heat up from friction the shaft expands more than the sleeve, and the clearance gets narrower, until the noise stops. If you shut down and re-start right away with the fan still warmed up, you get no noise. But shut down for a long time to let it cool off, and the same story happens again. Over a long time, the length of the initial noise gets longer, until it always is noisy. After that the fan will simply seize up and not work at all.

The solution is to replace the fan. You cannot repair it. If this is a new thing and the initial noise is less than 5 minutes, it is not an emergency. But it WILL get worse, so plan to do the replacement some time.
 

inowaterpolo

Commendable
Sep 13, 2018
3
0
1,510
0
You may not be observing a fast fan. Just a NOISY fan.

Fan bearings wear as they are used and get older. This increases the clearance between the fan shaft and the bore in the bearing sleeve. Once that clearance gets too large, this is what happens.

When you first start up a COLD system the fan makes a lot of noise because the shaft is "rattling around" in the sleeve. But as the bearings heat up from friction the shaft expands more than the sleeve, and the clearance gets narrower, until the noise stops. If you shut down and re-start right away with the fan still warmed up, you get no noise. But shut down for a long time to let it cool off, and the same story happens again. Over a long time, the length of the initial noise gets longer, until it always is noisy. After that the fan will simply seize up and not work at all.

The solution is to replace the fan. You cannot repair it. If this is a new thing and the initial noise is less than 5 minutes, it is not an emergency. But it WILL get worse, so plan to do the replacement some time.
This makes sense. Gutted to hear that I need to replace the fan but thank you very much for the explanation, sir!
 

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