Computer doesnt boot when I use a GPU Riser

[jetplaness]

I just upgraded my CPU and motherboard from a x99 board and an i7-6850k to a z390 aorus ultra wifi board with a 9900hk and for whatever reason I get a red LED on my mobo saying VGA when i use a GPU riser cable. It worked perfectly fine on my other motherboard but when i switched it to the z390 i get a vga led light and it doesnt post. I also took out the riser cable and just ran the gpu straight to the mobo and it works fine. The gpu is a gtx 1080 if that matters as well. Does anyone know what might be causing this issue?

[GhostRoadieBL]

electro magnetic interference shielding will be different between the motherboards, your other board is probably using different power filtering or higher quality capacitors/pcie pins so it can filter the high electrical noise interference spike when powering on.