But I ran on finnish forums into a thread, where a person was looking for a quiet GTX 560 Ti, same as me. What I found after that was that people have complained a lot about the noise the GTX 560 Ti DirectCU II creates.
Tom's Hardware 3D noise charts for Gaming GPU's gives the value of 33,7 dB(A) (http://www.tomshardware.com/charts/2011-gaming-graphics...)
There are lots of factors in evaluating the dBA, methodology, position of microphones, speed of fans, etc. One thing that may cause a huge difference in evaluating a single card is fan speed which can be altered by a fan controller or software like MSI Afterburner.
The best way you can evaluate the difference between different models is to look for comparison reviews of different manufacturers and see which is recommended for quiet. Another way is to read the reviews on a site like Newegg and look at the reviews to see if there are complaints about noise.