I don’t know why you keep bringing up the new ivy-e Xs. Possibly pre-emptive Apple love? 
They are 6core (12 is HT virtual cores) for the decently clocked ones, and the 2643, the one hexacore with semi decent frequency is 1550$ when you buy tray.
They might be beasts for preview rendering style but only if you have high cycle per die needs, because cycle per buck they are horrendous and close to the absolute worst possible CPU you sould slap into a case.
Given OP’s budget of 3 to 3.5k I’d be more than hesitant recommending one spends more than half of it on what will be a CPU more than thrice as expensive as a top of the line i7 for maybe a 20-30% performance squeeze, if that.
On top of that if you want a single CPU and overclocking is an option they are simply not that good for rendering, and get absolutely smoked at single tasking by even a lowly i5k clocked respectably.
(unless the 2643 will be unlocked, in which case I’ll retract that last paragraph, but I haven’t found any indication either way).
Unless you mean the 2695, which is an actual 12 phys cores, but has a laughable base frequency and is 2.4k tray cost (street price practically the entire floor budget by OP). They are totally NOT meant to be good rendering CPUs, those are webfarm/computational centre CPUs for those with no license bounds and who have footprint and heat priorities.
They would be the only thing worse than the above mentioned 2643 bang for buck for a workstation, so I sincerely hope you weren’t suggesting that.
and that’s right below a rendering test 