See in "Original" to see the noise pattern clearly.

This is from the same RAW pictures as in the previous image. However the RAW converter is Digital Photo Professional. All noise reduction is again disabled, however the sharpening seems to be stronger. Despite of this the surfaces at very low ISO settings are much smoother. At higher ISO setting the noise is much coarser compared to Camera Raw. A rather interesting difference - the two converters must have a very different approach to the conversion.

Again the clipping is much stronger at ISO 50 than at ISO 100 +1EV.