I bought a new PC, I want to convert my old PC into a streaming PC. What do I need to order?

[spiral raptor]

The Pc I just bought and want to use for gaming:

https://nzxt.com/product/player-pc-3060-ti

Old Pc I want to use for streaming:

https://www.bestbuy.com/site/ibuypower-gaming-desktop-intel-core-i5-9400f-8gb-memory-nvidia-geforce-gtx-1650-super-1tb-hdd-240gb-ssd-black/6400463.p?skuId=6400463

I know I need a usb switch for my keyboard and mouse, I have the elgato capture card worked out and I know how I am going to make all of that work and stuff