I have a Dell Precision T3500 that I wanted to start with that is still entirely functional. It has a Xeon W3530 2.8GHz processor, 24GB DDR3 1333 RAM, 256GB SSD, Windows 10, Quadro FX580 graphics ...

This system shipped with a maximum of 24GB RAM, and that's still what Dell specifies. It's an Arrandale CPU-- think the Xeon version of Bloomfield Nehalem/Core i7 900 series. Intel likewise says ...