Today I started up my pc as normal, but after about 20 seconds of being on, a vibrating noise comes on inside the computer, sort of like a cable is skimming a fan or a vibrating piece of something is being obstructed. The sound only comes after the computer boots to login screen and from waht i can tell, its from a fan, although thats just a guess. I opened up my computer and wiggle around the cables so they were clear of everything and checked all the fans, which are all solid and not wobbling or blocked. AFter this, i still had the same sound. I have a video of the sound, it would help to watch the whole video because the sound does vary throught the video, and at the end the computer shuts off. I narrowed it down to the fan in the back of the computer (not psu, cpu or gpu fan) becasue when the sound goes away when the computer shuts off, it is in sync with that rear fan stopping its rotation. thanks for any help!