Heat output
To test the efficiency of the cooling solution we placed a thermal probe about 6 cm from the backside of the case and another one in the middle of the case on the bottom.
As you can see Crossfire does an awesome job keeping the case inside cool, with just a few °C above ambient. The QuadSLI cooler seems to put a good amount of air inside the case, this may be because the two on-board connectors block some of the outgoing airflow which probably goes back into the case then.