Fan case position

Hi guys, i need an input here.

I have a really powerfull 120mm fan (i mean really powerful because the airflow can take up to 3x than normal 120mm fan because it use huge dynamo and independent electricity) where should i put this fan to make it efficient? In the front or in the back as an exhaust?

Really need input here. Thanxs.

BACK , most of ur hot parts are located near the back liek the cpu and power supply and ur videocard plus it exhausts directly out so if the fan was in front it wont have anything blocking the path of the air flow