I have an older MGE Viper case. It has 3 places for fans: 120mm rear, 120mm front, and 80mm side. Imgur Case layout and available fans ... excuse the crude image but I wanted to have a visual on my set up.
Currently I just have the case and I have the parts I ordered on the way. I will have have two fans: 120mm 3-speed (39/56/79 CFM), 80mm (25.6 CFM). I have an i5-4570 with a Hyper 212 EVO and a XFX R9-280X-TDFD that has two fans. The PSU will be a 750W modular.
Since this will be used in a hot environment, I think a negative air pressure configuration will be the best. What is the best configuration I can have? If the side fan location will be used, should it be an intake or exhaust? Should I use the 120mm fan in the rear exhaust and use the 80mm in the front intake? Or is it better to get another 120mm fan? What speed or CFM should I get?