Depends on you. If you put the radiator on the bottom/front, it should pull in, on the top, push out, either way, you should push through the radiator. On top, your ambient from the other stuff making heat in the case will be slightly higher than your front/bottom pulling cool air in. However, temp differences will be minimal, and would be noticeable when your graphics card is getting a workout, maybe. I haven't tested it, but that's the theory. Most people put their radiators on the top, me included, cause at least in my case, that's the only place I can fit it. But ya, up to you, won't make much difference if you've got decent airflow.