Welcome to SPCR!
Why so many HDDs? If there is any fans in that case I bet they need to be replaced
For DVD i can recommend Samsung SH-S183. Rather short, has SATA and suprisingly quiet
I agree on the case fans. A silent 120mm for exhaust, is pretty easy to find. Nexus or Noctua for ex.
But a good 80mm is much harder. Probably Akasa, amber series or Nexus would be the best bet.
I also wonder why you need all those hd's?
If it is for backup and storage? Then it's better to get a couple of external USB enclosures for the hd's you intend to use for backup.
This will lower the case temp / noise. And you can have those external usb hdds on and off by will.