Upgrade advice for new PC for a 5090

[Rhaos]

Hi all,

Can someone spec me a build please. I'm asking for a friend as he wants to build a new system for a NVidia 5090.

Either Intel or AMD CPU plus motherboard
64GB RAM,
4TB SSD,
PSU good enough for the 5090.
PC Case

I'm not to clued up on what the best CPU Motherboard combos are at the moment so an help appreciated.

Thanks