Ok, why so slim a fan? Make it as thick as the space between the towers. Dual behemoths are not needed anyway, not unless you're running lga2011x.
Also, AIO watercooling the CPU is pointless. The CPU area is big enough for a cooler for god's sake.
On the other hand, AIO watercooling the GPU is NOT pointless at all. Glad almost nobody's doing it.