All of the reviewers say that the asus card can't be heard when in a silent enclosure like the fractal R4
Never trust other sites when they say things like that.
Techpowerup is good in their noise measurement technique, though they rarely get into characterizing it -- ie, when the SPL is close, often, the lower number doesn't necessarily sound quieter due to tonality or other aspects of noise other than "level" or amplitude. They also measure the noise during gaming loop peaks. This might actually be more realistic than SPCR because we use furmark, which loads the GPU to the absolute max, higher than in games.
I agree, though, that if you want lowest noise, go for the cheapest card w/ the GPU of your choice & add a good aftermarket cooler.