hdparm -y /dev/sdb # to the rescue for the silence

turns out I could simply reorganize my mounts and spin down my hdd. Now at last can I enjoy the silence...

If I try to listen carefully I can only hear street noises from across the river and a few 9-stores buildings [something ~600 meters] through a closed plastic window and absolutely nothing from my PC.

Now.. Next mission: how to silence those street noises...