Haha, fan cooling was always my biggest and constant worry (not to mention dust), of course my case has 6 bays to play with. I have a Cooler Master N520 (haven't used my computer in a couple years, impressed I remembered the model number first try) and Thermaltake V3. So it's a tight fit trying to get much else in no matter how I go or around the N520 beast... but I do think my last change was RAM > Heatsink > Back.
But I always assumed that having it like that if I exhaust from the top above the RAM that it could cause a pocket in air flow, and at the time... all my super thin fans with best airflow, kept dying so fast for their $30/ea. price tag. You live and you learn.