Loud rear chassis fan on cold startup only

[xizzboy]

My pc used to startup quietly, after a very hot summer and with the arrival of the cold weather of autumn with rain and moisture, it started making a very loud noise during 2 minutes (or so) at startup and on the first boot of the day, then it quiets down and runs normal, fan doesn't make any noise at startup when the computer is already on and i turn it off and then power it up again (warm boot), then i decided to check the fan speed on bios or hw monitor software, my surprise, since this fan is not controllable (3 pins) and always runs at 100% at 1900 rpm, bios or hwmonitor reported 1200 rpm on startup, then progressively the speed increases until 1900 (1200 - 1250 - 1400 ...) once reaches 1900 noise is gone and runs normal and silent, this is very strange and different from what other users with similar problem report since my fan doesn't start at 100% RPM what suppose to, starts at lower speed and makes noise because of that, my first thoughts is fan rotor failing, but i really don't know, should think about a new fan? Any thoughts?

 

[wogfor]

I think I would go ahead and replace the fan since you have already determined that the fan is making the noise, it's likely whatever it has for a lubricant has either died up or become thickened. I would think the latter as you described it, that it runs faster after "warming up" I would also pick a fan that's a bit of a better quality as it would tend to be quieter at the speeds you describe.

 

[Paperdoc]

What you describe is a classic set of symptoms of a fan with bearings wearing out. With worn sleeve bearings, there is too much clearance between the shaft and the bearing sleeve when the system is cold. When you start up the shaft rattles around in the sleeve making a lot of noise, and causing excess friction on the bearings to slow the motor down. But as the fan heats up, the shaft expands more than the sleeve, and soon the excess clearance is reduced so it can turn smoothly. It will keep working that way until it cools off again.

Your fan is wearing out and needs to be replaced. It will not suddenly stop soon, but it will continue to get worse, so plan now for replacement.

 

[xizzboy]

Thanks, seems it's time for a new fan

 

[Paperdoc]

Thanks for Best Solution.

You say the fan is "not controllable" because it is a 3-pin fan. Well, IF you want to, there are two ways to fix that as you buy a replacement. The first, obviously, is to get a 4-pin fan as replacement. The other MY be do-able. IF your mobo can use Voltage Control Mode (aka DC Mode) on that fan header instead of PWM Mode, you can control a 3-pin fan. Post back here what mobo - maker and exact model number - and we can check whrther that last option is possible for you.