Boot Manager disappears after installing new 5070-TI.

I was so excited to plug in my new GPU just to have my system not being able to boot Win11 after.

MB: B450-A MAX CPU: Ryzen 7 3800X RAM: DDR4 32GB PSU: rm1000x OLD GPU: 1660-TI (System works fine with that one)

No issues with my old GPU. My system should be perfectly compatible.. yeah I know, bottlenecking hard, but that shouldn't prevent a proper boot.

I can only access BIOS with the new GPU. And reinstalling the old one is a hassle because the Boot Manager stays gone until I leave my System powered off for like 30 minutes or so.

It's just so weird, I don't get it!

Anyone know what could be causing this issue?