from my understanding, all vents suck in cool air (not blowing it out) and the back vents (when lying down) blow out the hot air so that's the most important vent that needs to have room.
as for the disk drive, i think that's supposed to be the hottest part no?
and why are you saying it's still loud? you cleaned it out? or has it always been loud? or is it louder than usual? anyway, i'm no expert about opening it up and cleaning up the guts, i typically pass a vaccuum by the vents every once in a while.







