Intending to fit a couple of 120mm fans with a temp controller. I understand that it is better to fit these on the top vent to suck out the hot air. But I have not seen a definitive answer to if the two fans are just bolted to the inside of the existing vent cover, ie with air gaps all round them so hot air can escape either thro the fans or past the fans. OR fitted into a custom built plate which only has a gap for the fan exhausts, then this is bolted to the back of the vent cover, ie all the hot air must go thro the fans. Any thoughts ?