[300winmag]

Now it's the front case fan that seems to be making the most noise.

Try a foam gasket for that fan. You might even be able to make your own if you have some sort of thin foam material around the house, like that pink stuff used to wrap electronics with.

[Overtaxed]

Okay...will try. I can try that foam-type material that comes packed in the glass pipet boxes from werk.