Have you checked the HDD temperatures? HDtune should be able to do that, or speedfan can.
There is a frame in the lower middle, it's visible in some of my pictures I linked to. It's similar to the mounting frame for the front fan position, perhaps even identical, I can't remember.
There is a frame in the lower middle, it's visible in some of my pictures I linked to. It's similar to the mounting frame for the front fan position, perhaps even identical, I can't remember.

