Small update:
I was able to clone the old SSD so now I have the exact same software as the old PC, same GPU, same hdmi cable, and same monitor.
After an hour I am in terrible condition so something is not working.
The NZXT X73 liquid cooling pump is making a noise that is driving me crazy, tomorrow I get the corsair H150i! I would like to hope that the problem was related to that noise but I doubt it....
The alternative is that the motherboard is doing something different in the PCI-E slot! But it's a gen 4 like my old motherboard....
I feel like I threw away 2000 euro, so sad!