The Asus Strix card is the quietest as its fans don't spin at all when the temperature is below 67c. At load, it's a full 10 dBA quieter than the EVGA SC with the ACX 2.0 cooler (29 dBA vs. 39 dBA). The Strix card scored a nearly perfect 9.9/10 at TechPowerUp.
Quote:
"ASUS engineered their STRIX series with a unique feature. With the card in idle or a light load, the fans will stop completely, providing a perfect, noiseless experience. Once temperatures exceed 67°C, the fans will spin up, but do so very quietly. Even while gaming at full tilt, with a full load, the ASUS STRIX GTX 970 is extremely quiet, barely audible, no matter what you throw at it. Good job, ASUS!"
http://www.techpowerup.com/reviews/ASUS/GTX_970_STRIX_OC/24.html...