But keep in mind that xeons don't have an igpu, so you will need a dgpu to use the system, iirc. And if you weren't going to put a dgpu in there anyway, that can add a bit to the cost, so then something like an i7 or i5 some sense.
Well there are even Xeon E3's which do have an igpu, but these are a bit more expensive.
Xeon E3-1276-V3 for example.
This chip has also a turbo clock upto 4Ghz by the way.