I've had a really good read through this topic, and i can't see anyone reporting the same problem as me, so here goes.
I have 4 hard drives installed in this sort of configuration ( x represents a dirve and | is blank )
x | x
x | x
Now, the problem I have is that the whole case seems to be vibrating to the sound of the hard drives, and I get this really annoying pulsating noise. I've cut it down a bit by using foam padding on either side of the drive in the holders against the aluminium brackets, but I really don't think the case should be vibrating like this.
If anyone could help me figure out what is causing this I would be most grateful, thanks.