I dont know anymore...

Hey Guys. I Upgraded my CPU from 3600x to a 5800x3d. I did the BIOS Upgrade to the newest Version in advance and did a CMOS restart after installing tge new CPU. I tried to boot Up, But i get no picture and the CPU-LED Lights Up for half a second then switches Off and the DRAM-LED Lights up. I tried everything. Took the RAMs out, Put Just 1 in. Took another RAM Kit, Put it in. CMOS and complete BIOS reset by taking Out the battery. I then thought maybe its a Problem with the BIOS Version as its the Last Thing that could be possible, so i re-installed my old 3600x to flash another BIOS Version and i got the Same BS with my old CPU now aswell. No picture, CPU LED and then the DRAM LED. I also have No flashback with my mobo so i cant even do that. Anyone has any Idea what more i could try?

Thanks in advance.

Specs: Gigabyte aorus b450 Elite V1 Corsair vengeance 3600 ddr4 RAM Ryzen 7 5800x3d Radeon RX6900xt

         650watts Power supply.