http://www.cyberphoto.se/?info.php?article=K-5
Or, view Google translated English page here.
Click on the second tab and you will see some samples, including two sets of ISO shots, with NR at default and NR being off. The lens used is DA*55/1.4 (Not "FA 55/1.4", which is non-existent!).
Well, you can see that actually when the NR is turned off, the noise level of the K-5 sensor is not as low as one would imagine and they are still there, especially at the darker areas.