I recently installed a new CPU cooler, it works great but the CPU fan is quite noisy when I start the PC after it's been off for a while. To be clear, it's not a matter of fan speed, yes the overall noise is louder when speed is higher, but the noise it makes the first few minutes is there regardless of the speed. For the rest of the time it's very quiet at both low and high rpm, and the noise never come back unless I leave the PC off for hours.
I've tried touching the case of the fan both when it was making noise and when it was not, but I wasn't able to spot any difference in amount of vibrations.
The cooler was used, and very very cheap so it doesn't make sense for me to try to get a refund. Those two minutes of noise every day doesn't really bother me but I'm just curios on what could cause it, and if it could in any way harm the rest of the system.
This is the fan model: http://www.coolermaster.com/cooling/case-fan/blade-master-92/