These cheap older xeon chips are interesting but the trick is really to find a cheap motherboard that can support one. The reason they are so cheap is because its hard to find a decent motherboard to use one with. That said there are a few 6 core xeons that can overclock and those are the ones you want to look at. I think the one you mentioned is probably one of them, but I'm not sure.
That said, you would be a lot better off to just overclock your current CPU to 4ghz and get a better GPU. Unless your going 120hz+ 1080p gaming, your CPU would hold up just fine with a decent overclock.
Edit: I see you say this is not for gaming. What is it for?
i7 7700kK @4.2ghz
16GB DDR4 3200mhz
GeForce 1080 Ti