I want to build a PC for inference and training of Local LLMs and Gaming. I've decided to go with an RTX 4090 and a used RTX 3090 for 48GB VRAM for loading larger models as well as a decent enough speed.
What motherboard, PSU and Cabinet should I choose? Ideally I'd want to run both cards at least with x8 PCIe slots and will also add 128GB DDR5 RAM in this build.
Also, should I go with Intel i9-13900K CPU or with a Ryzen variant?
Thanks.