1 - With a help of a soldering gun I take off stock fan by putting it in the middle hole
2 - Then I melted the four plastic pieces on Noctua fan (warranty gone

3 - I take off the fan from his base
4 - Once again with the same soldering gun, I cut the middle of the base
5 - I cut the stock connector, soldered to the new fan and I glued new fan to old base.
6 - And last step, I mounted the combined fan to XU4 with original screws

The original case is fitting perfectly.
Like in other thread, the fan spins in the opposite direction but it's ok, it's quieter than original.
I have to try this script to see if get better results https://github.com/nthx/odroid-xu3-fan-control