Personally I have had great success with a single front intake fan, a rear exhaust, and my inter-cooler mounted on the top with 2 fans in a push configuration, exhausting air out the top. I try to keep just enough air coming in to unsettle the ambient temperature, but then rely on the dedicated cooling of my graphics cards and processor liquid cooler to remove the heat just from those components. It also helps to have SSD's also as they generate much less heat than standard spinning HDD's. I also have experienced much less dust buildup since switching to this configuration on my last three builds.