Quoting Noctua

I'm also glad to hear that you like the new backplate and the improvements of the mounting system. We'll also include self-adhesive washers to make the installation process easier in the future. The new mounting parts will also be included with the NH-U12P by the way.

I'd also like to comment on the clearance for mainboard components and on the fin-spacing: Since the NH-U9B is quite a bit lower, we had to pack the fins a little tighter in order to keep the overall surface area large enough so that the cooler can cope with higher heat loads. The same thing goes for the smaller clearance underneath the fin stack. Due to the smaller size of the NH-U9B, this doesn't result in compatibility issues because it nicely fits into the 95mm LGA square that has a maximum component height of 25mm.