No coincidence the new ACX cooler is set to debut on 5/23/13, the same day the GTX 780 is released.
I think EVGA is finally realizing that their typical reference coolers are in need of an upgrade. No matter what upgrades they put into their PCB's and components, that reference cooler always put them a step behind in terms of perception.
Actually its not the coolers holding back overclocks its nvidias lockdown of the voltage and not allowing its partners to alter the pcb . The only point of putting a new cooler on the card is if it performs the same but can do it with less noise. Overclock won't be any different as it's voltage limited not heat limited.
Actually I have been pleased with the reference cooler design on my EVGA factory o/c 680. Granted when upping the fan speed above 75% it can sound like a dust buster, but I either wear headphones or have my 5.1 speakers blaring when gaming and can't hear it under load. Exiting hot air out of the case is a better than having two or three fans blowing internally on the GPU.