Quietest is Sapphire Trixx if you just buy the retail box version with respect to other retail version.
If modded with water cooling , any card can be the quietest as long as you use silent fans on the radiator.
Yep... I'm actually thinking about getting NZXT water-cooling for my card later half of the year. Heard they have a special bracket for GFX cards that makes it alot more hassle free to install water cooling.
It's either Toxic or twin frozr...
Never heard of Toxic before