From what I understand and can see, optical drives don't put out that much heat. HDD somewhat, but not as much as your core parts (CPU, ram?, mobo, ect...) These are the biggers. Also, optical drives on bottom are asking me personally to break my drive. I always have a little something for it to catch on. But that is just me. Some put their case on the floor, so that to me is asking for trouble. I mount my drive there to because I have the 8800GTX, which is a baheameth in size. This lets me stablize my airflow as well. I have a little more manageing to do, but its fairly good. Just don't crap hang out all over and you should be fine. EDIT: Ill post my pics and crap when I'm not feeling lazy one day.