No probs with the HDD's beside the PA.
They are only in contact with the outer frame which is cold anyway.
This case is so chilled its unbelievable!
The only thing is that they are a tight sqeeze.

As I said earlier there are options on the HDD's which are in the photo below.
Myself I plan on going for SSD's in the near future so that should eradicate more noise and heat.