That "cone" is an inlet air guide for the CPU cooler, not an exhaust. What problem are you trying to solve? If its cooling the CPU, you would be better off replacing the stock Intel cooler with something like http://www.newegg.com/Product/Product.aspx?Item=N82E16835186134
, its inexpensive, easy to install, and works much better than the Intel piece of crap. Make sure you use a good TIM, something like Arctic Silver 5 or a similar product. You haven't indicated what other cooling fans you have in your case, however a fan at the CPU inlet duct is of minimal value.