I called the store again today and i told that i made a topic here. And tryed everything you told me.
I get a new motherboard, and if they have time they will test the new board (i asked that because i want to avoid that it is not working again maybey) so i think the problem is getting solved.
Still i am wondering what happend to the board.
First time power on it rebooted 3 times by mobo self.
4th boot in windows.
After reset with the motherboard reset button a FF status on the bios onboard status leds.
But i think the first 3 auto reboots without toching the reset button is no good either.
I have inspected the corsair 500r case and there is enough room between the board and the case,
So no change that the board hits the case, original standoffs not adding other ones.
I must say that i am scared now for the new one
Did sleep verry bad last night.