Buzzing noise from under keyboard when fans spin up
Hi, I have recently replaced my HDD with an SSD and then I replaced my optical drive with the old HDD.
Everything seemed to be fine but then every time the fans spinned up I could hear a loud buzzing noise coming from under the keyboard.
If I put my fingers above the keyboard, in the space between it and the hinge, and perform a very slight pressure then the noise stops (but then starts again if i remove my fingers).
At first I thought the culprit was the optibay adapter, so I removed it and restored the original optical drive, but this proved not to be true.
So I've tightened a bit more the bottom case screws and now most of the times the fans spin up everything is fine, yet some other times I still get the buzzing noise (but much more less audible).
At the beginning the noise was not tolerable but now, after tightening the screws I think i can live with it.
Anyway I was wondering what could be the cause of this behaviour, and how can I solve it.
I've read some other people had problems due to failing fans, but from what I could observe I don't think this is my case.
Is this a good question?