I've gone through POWERCOLOR PCS++ AX5870 and GIGABYTE GV-R587SO-1GD. They both disappointed me greatly. Powercolor HD5870 had a faulty fan and Gigabyte HD5870 had high idle fan speed. I just couldn't put up with such noisy 80mm fans.
I don't care if the card is overclockable or not. Even temperature doesn't bother me. I just want the quietest possible HD5870 model. What should I get?
Sapphire Vapor-X was actually at the top of my list until I read some reviews saying that at idle, its fan runs faster and thus noisier than the stock design. I could be wrong though. Newegg reviews are not always trustworthy.
I forgot to mention that even when you are watching HD video content, it still is at 21%.
Also, if your ambient temp is higher than 23c, don't worry, when it's hot in my room, the gpu can get to 38c at idle, and still the fan is at 21% so...I think this is what you are looking for