me and my dad upgraded a guys pc and this is what we got for him but he had a few things that we could use from his old pc
Mobo
Ram x2
Cpu or you could use your's that you have now iirc
we had to get a new psu for him but the lot came to around £140 obviously there might, be better options but for him it was fine he doesnt game or anything but he likes it for, what he does and really without going to expensive it wasn't bad and all you would need to add to it is either agp or pci-e graphics and a psu.
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7900X3D, 64Gb Corsair 6000Mhz, Gigabyte Aorus RTX 4080 Super, Samsung 980 Pro 2Tb NVME
Unraid Server, 130TB Supermicro CSE-846, AMD Epyc 7551P 32 Core, 64Gb ECC DDR4, nVidia RTX A2000