B550I AORUS PRO AX: no post, no video

Hello,
i have the following Problem and went down a rabbit hole:

i Build a new home server with the following specs:

gigabyte b550i pro ax rev 1.3
5700x
64 gb ecc ram from samsung
yeston rtx 3050 (the small half/ single slot one)

I flashed the bios with q flash plus which worked as everyone said where the outside led blinks and stopps after 5 min and then the pc turned on. i dont have a riser cable for the gpu. yes i inserted the hdmi into the gpu, not the mainboard. i flashed the bios again without anything expect power. i installed ram and gpu into another Computer where they were detected and worked as expected. when i stard the computer every fan spins, but i cant get it to post or get any form of video output. i tested different monitors, different cables and different power supplys. still i cant get it to post or get a video output.
my guess would have been that pcie has different settting from mainboard and gpu. But i thought it would still be at least detected.
Does anyone have an idea? i am at an end.

Thank you for reading.