That is, as the load goes up so do most cooling fans. You can find reams of posts about finding noises in PCs but with a little care you can wait for the noise and then stop the fan to see which it is. Here's a post on that. Be sure not to stop it via a fan blade.
https://www.google.com/#q=find+noisy+fan+with+pencil+eraser
I got a new Gaming PC a few weeks ago (about 7) and I noticed when I played games that used more then 50% of my CPU a noise would begin. It's a squeaking sound but not like fingers on chalkboards. Other forums say it's my fan but I just got it. I just wish i could show you the sound. Because it's not a loud squeaking, and it doesn't sound like it destroying anything.
Thanks.

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