I ended up putting a 120mm fan directly to my 4870x2 that was restarting my rig because of high temps. The lower part of the case has some cooling issues IMO. What i did solved the temp problems i had, but it was a design flaw on the card as well i think.

The cosmos S has bays all the way to the top of the case, right? YOu might be able to put in some more intake fans there, and route the airflow if those bays are empty.

Pics would be helpful so we can see how it stands right now.