Buying into NVIDIA for Robotics Dev, need advice on DL PC build

Creating robots that use neural nets requires a deep learning pc. NVIDIA is selected as my “all-in-one” resource for for my endeavor. To learn and run NVIDIA products, I am building a DL pc, and am looking for advice on specific parts, or best build recommendations. Currently I am leaning towards using only one 3090 GPU blower type, but want to be ready to add more as needed.

There are of course other resources to discover what I need, but I thought; where else to get the best advice about the type of computer build needed to use NVIDIA products and their learning facilities? Hopefully you can help me.