If you look
here you will se in the top right my A4000d befor I towerised it I placed a large 80mm fan on the outside of the case neer the front on the left side Pulling air through the case. This worked wonders at keeping my Video Toaster cards cool. I placed another smaller fan pushing air in on the right side right where the CDrom and the power supply meet (there is a space just below the CDrom drive perfect for a small 40mm fan).
I used my Dremal to cut out the proper circle for the fans.