Thanks for all the thoughts. The 10gbit portion would be less about need and more about desire 
I am not dedicated to linux or BSD over windows. I am perfectly happy with used hardware. I had considered the noise factor but I had thought there would be a quiet enough option. I hadn’t really thought about trying to fit a desktop in the cabinet. At the moment everything inside stays a decent temperature without turning on the cabinets built in fans which is nice since they are not silent. I am looking now and if I move my modem (which is neatly sit atop my dream machine pro) there is exactly 4U of space there. I had planned on said machine being purely for capturing video but I may have to give it more of a purpose if I am going to have it take up 4U of space the other thing I was thinking was the machine in question if it was just for capture would not be on 24/7 only when recording so noise may not be as big a concern. IDK a lot to think about. I need to finish setting up the HDMI KVM switch for now and I will keep considering the final options. Thanks for all the input and any further input y’all have 