Corsair Building Cases! The 800D
I think the airflow would be easy to get going the right way actually. I like this case a lot. With 4 fans installed on delivery and the awesome cable management and WC ports, it's a definite look at when released. If you notice, there's actually a vent under the bottom expansion slot for double slot GPUs in the bottom expansion slot. I have seen no Cases with this as of yet and i've been looking for the P6N Diamond I have with 4 GTS250s on it. The main challenge would be if you water cool multiple GPUs getting air around the Ram/Voltage heatsinks on the GPUs. It could be easily fixed, but more challenging to do in a visually pleasing way with that HUGE side window.