Yay, easy fix!

Computer is not borked after all, there were just some cables hanging down and hitting the fan. Fan is not broken, and they just needed to adjust the zip-ties keeping the cables together and presto, no more loud noise. Evidently it's a common thing and if they ever fall down in the way again, it's something I can easily fix myself. Also a good thing to know if I ever bother to do the research and make the effort to build my own comp in the future. I keep meaning to try, but I'm lazy about it.