New cpu, gpu doesn't work

[Drakonins]

Hello, so I got new cpu and motherboard. 

R7 5800x3d

Msi b550 tomahawk

With rtx 3090 monitor doesn't turn on. 

With rx 580 it turns on. 

With older cpu 3090 turns on. 

Older cpu's integrated gpu turns on monitor. 

Bios for motherboard has been updated to last version and older versions have been tried. 

Ram 2 types have been tried. 

On motherboard error code says that there is something with ram or gpu.

Gpu isn't over clocked or undervolted. 

Bios is clean with nothing done to it. 

Tomorrow I'll try to connect to different pcie slot and without pcie extension cable. 

Any ideas what else I could try?