What's powering whatever's going into the cabinet?
Identical fans for intake and exhaust is not a good design. Use all 4 as one or the other. Depends on how the layout affects airflow. I usually like exhaust fans up top, but if you know it's going in a dusty environment, intake fans you can put filters on are better and a 'leaky' box isn't going to take in dust from its crevices because there will be pressure working from inside.