There are a couple of places to put a fan to help with cooling. You can put one in the side panel in a spot so as to blow directly onto the two cards. If there is no precut hole for a fan then you can make one , the side panel of the case is pretty thin metal and cuts very easy. If you have a window then you can cut that as well , it just takes patience and being careful. If you have a Dremmel tool then it becomes even easier.
The other place is attached to the hard drive rack so as to blow towards the back of the case and aimed at the end of the cards.