Actually I'm starting to think the alim actually died and killed either
-the MB
-or the videocard
or maybe just the BIOS , i don't know i'm not an expert.
since -.. is supposed to mean "no videocard detected".
I've tried many things excepted try another videocard since I have none. And anyway I won't buy another one as long as I have a warranty.
I decided if I don't find a solution with what I have I'll replace the original alim, and send the pc back to the support. That means : certainly a long wait until I have the pc back again... I'm happy I didn't sell my previous pc.
That sucks, unexpectable, never had such a problem.