VGA cooling in general is noisy, even suppposedly quiet coolers from asus etc. i did have a msi card which ran very quiet, but they have since changed to noiser fans in the new models. the only solution is something like mk23 from Prolimatech which can run inaudibly on my 680 (using pwm noctua nfs12a) and doesn't spin up, ever. As far as case fans, unless you need a child or pet friendly solution open case works best. If the vga and cpu cooling is inaudible, there is no noise and you save money and noise on case fans.
I never had much luck with larger fans, 12cm is a sweet spot for silent fans, save for some 200mm fans I haven't used.
My GTX670 with an ASUS DirectCUII cooler is incredibly quiet. It idles at 30 degrees at 10% fan speed. Even at load it's amazingly cool and quiet compared with my CPU cooler (Hyper212+) which is already quieter than stock.