They did replace my PSU to the stronger one. But they said i connected the GFX in the wrong way. I connected it with an external cable from my GFX to my PSU. Later on they commented that there is an connected cable in my PSU that i need to connect so the GFX would have more and better power. The PCI cable or something.
So after all only the PSU is switched and nothing else.
Thanks again and as u can see, together we fixed it.
We meet again,
Rolán van Melis