dada666 I'm no expert, but strange artifacts on the screen normally mean a problem with your gpu, and since the problem persists across two different distros it definitely sounds more hardware related than software.
If while your computer is booting up you continuously press f12 key over and over again are you able to get into your bios? Or is there just no signal going to the display at all?
Do you have a second graphics card you could try hot swapping in if you have to?