GOT A couple of ideas that would improve performance and probably beat out the Noctua NH-D15
1st - the fins should have some baffles or louvers, like the red lines, to help the air flow establish a flow path that is parallel to the fins - entering the fins the way it is, the air flow is going to experience some turbelence and not scrub heat off the fins as well s it could. Look at the water cooled racing bikes like the Hondas - they have louvers or slats in front of the radiators similiar to the red lines i've drawn, as the radiators are mounted to the front rake tube on the frame and not perpendicular to the air flow. Those slats do exactly what i'm describing above, helping the air flow to establish a flow path parallel to the fins.
I only drew slats or louvers on one side, picture the fins will slats on both fin banks
2nd, the ends should be shrouded so that "V" valley is closed off, shrouded from the fan down to the bottom edge of the fins and shrouded on both ends.
3rd, and this is the mod that i think would give the biggest bang in terms of efficiency but would require modifying your case. This mod also assumes the mobo is mounted vertically. As the height is 147mm to the top of the fan, that's going to put it within 13mm (1/2") of my case's side panel, which means the fan is going to be struggling to pull air in to feed the fins.
But being so close to the computer case's side panel, it'd sure be easy to cut an opening to let that fan draw in fresh room air - that would probably give the biggest boost in performance.
anyway, fwiw