Target 6000 speed for your RAM. AM5 is notoriously picky about RAM in general, and people seem to have the best luck with that. I have a 4070S with my 7800 and it's incredible, crushes anything I throw at it with games. Can only imagine how cool a 4090 would be!
Main problem I've ran into was boot issues. It just takes a while.. a long while. But sometimes it just wouldn't post. Turned out it hated my RAM. I bought a kit that was XMP optimized, and my Asus board was running it under DOCP, but it just wasn't stable. I have to admit, I didnt even know there was a difference in RAM. Returned it for an EXPO-Optimized set (G.Skill Trident Z5 RGB 64 GB (2 x 32 GB) DDR5-6400 CL32 Memory) and no problems.
Another small thing is you can very safely undervolt the 7800X3D. You can just set all core to -20 and forget about it. This has a fairly decent positive impact overall. I turn off PBO and some other things as they literally do absolutely nothing, or even have a negative impact on thermals (with no added performance). Good luck, sick build!