Case Air Circulation Help!

Hi,I'm a newbie,and I've recently built a computer. I used an Antec Sonata III case with its included fan moving air out of the case in the back,and i added an additional 120mm fan in the front to pull air in the case. I also have a ZEROtherm BTF90 cpu cooler,and i'm wondering which way should i face the fan on the cooler. I know facing the fan to the back of the case is idea,but due to the Coppers fins on my Asus M2N32 SLI mobo and the RAM, i can't really orient the BTF90 to face the back.If i try to do that, half of the copper base of the cooler wont even make contact to the cpu,and that's a really bad thing from what i understand. the only choices i have are to face the fan up or down(like to the top of the case or to the bottom,towards the graphics cards). Which way should i put it?Thank you so much.

sankyuu~~