Just to update you with my experiments. I wanted push/pull fans specifically to run off the fan header on the graphics card, as my motherboard only has one fan curve based on CPU temp (asus fan xpert II). Hopefully one day we will be able to modify this curve with afterburner/GPU tweak.
I tried a number of 3/4 pin fans but none worked. The only that worked off it were corsair sp120 performance fans (3 pin, not pwm). I suspect because the ampage was more similar to the stock fan. With these in push pull it's cooler and the sound is quieter and also has a more tolerable tonal quality than the stock. Hope this helps.