AM5 Motherboard Suggestions

I bought 64GB DDR5 RAM in 2024 thinking I'll be building a new PC. Didn't build one and I still have the RAM. I want to use this now and am set on getting 9950x3D.

My use case is about 30% gaming, 40% video editing, rest use case is browsing, running emulator.

I built my current PC in 2016 with i7-6700K with 32GB of RAM. Storage and graphics card have been added and changed over years. Currently have 512GB NVMe, 4TB NVMe and a few TB of HDD and AMD 5700 GPU. The PC is still running solid. If I build a new PC, this will end up being a server for various purpose at home and to run emulator.

1. Should I commit to X870E motherboard? If so, what would be the recommendation?
2. Considering the GPU prices, I'm planning to hold on to the 5700. Thoughts or recommendation? I don't need the best GPU as most games I play run great with some settings lowered. I'll probably upgrade the GPU when prices look reasonable.

Motherboard is what I'm totally confused about. Another worst case scenario (probably won't make me happy) is to sell the RAM at current prices and hope that current PC runs for another 2 years or so!

Thanks!