Because the problem is that before they were always under the control of the AMD catalyst, and guess what , I did what you told me again about the DDU and installed older drivers because the ones I had were ones with an acronym "Q2" or something and I remembered me that the ones that were before didn't have that name but some numbers.
CONCLUSION RESOLVED. Now I can control my fan curve with the catalyst, the fans are back to normal with the 2 screens on thanks to you.
Thank you all!
Big hug,
youthmp.