Proxmox server build part verification

I posted on reddit but I was recommended to post here by bot, so here I am.

I converted by current set up to run only freenas so I am in process to build another one to run PROXMOX for VMs.

Here is what it will look like. I already has case and power supply and SSD. my budget is $400. If something can be changed or removed, I will take in consider and can CPU cooler be cheaper? Seems like too much for that.