CPU Cooler Making Noise/Vibrating?

[Dajjjark]

Recently my CPU fan has been making a loud noise on startup from what seems to be vibrating. It never did this before, but for the past few days it has. I've also noticed that after startup when my PC has fully loaded it seems to go back to normal. Any help?

 

[WrektGlitch]

Sounds like a balance issue. Mine did the same thing, and I powered down immediately, opened the case, and pressed gently on the fan to make sure it was secure. Fired it back up, and it was fixed, and hasn't happened since. Not saying this will definitely work for you, but it may be worth a shot.