Mining Rig not booting up when GPU is connected

Hi All…newbie miner here. I just built my first mining rig using a MSI Z390 A - Pro motherboard. I have HiveOS installed on SSD and it boots up fine without the GPU (3060 ti), but when I connect the GPU the mining rig doesn’t boot up and all I get is a blank screen. No error message and it won’t let me get into the BIOS.

On bootup I see the GPU lights turn on and fan turns for about 5 seconds, then it stops and nothing else happens. I’m using an ASUS Geoforce RTX 3060 ti GPU.

I’ve switched out the riser twice but no luck. Any suggestions?