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#21
Thanks for the help Ciara and Linnemeyerhere :)
I'd go for a neutral airflow. I have two 90mm Vantec fans, one in the front bottom and one in the top rear below the power supply in my case. One brings cool air in and the other takes it right out. Best setup ever! If you don't know what the airflow ratings are for your two fans, I'd go with a negative airflow in your case. Take the two fans and run them together and see (or feel :)) which one has more suction/airflow. Then, take that fan and place it in the back.
But make sure that if it's your 120mm fan, it can fit in the back.