I decided to mount an external muffin fan on my 6300 -- the internal fan would keep kicking on once it reached 70c, making lots of noise. I bought a small, usb powered muffin fan and mounted it over the vents on the right hand side. I have the air blowing into the radio, and it is rather quiet. (I originally mounted it so that the air was being sucked out of the radio and it was VERY noisy.) It keeps the radio cool -- I monitor the temperature using Flex Stacks. Since I've done it, the internal fan hasn't come on even once.