Hi people i am looking into a proper NAS system or better known as Network-attached storage

I am slowly planning on building such a system but my mind is divided. Buying a NAS system with what is low powered CPU driving everything VS normal mother board CPU and PCI SATA expansion card. Now the tiny system you can buy looks cool takes little power and works. BUT everyone knows that bulk data WILL need high processing power at some point especially if you are running a network like mine. It is just a mess

So am thinking servers and server rack mounts and just do it properly. Industrial style server running 3 AMD system 1 for processing 1 for storage and 1 for Internet/firewall. All of them will be running 10 core systems with 64Gb of memory only one will be gaming speck. I am also looking at 12 X 3Tb Hard drives and 3 SSD for OS "Linux and 1 Windows system"

Have anybody done something like this before? Obviously it will be a year project but the goal is a proper server with backup, UPS protection and very high performance i am not going to go with intel they simply cost to much.