I'm at a cross roads on this. I'd rather not dump a bunch of $ into a rig build for several reasons, but it may be inevitable.

My rigs have the P9X79 Pro motherboard and i7 3930K. Would the XEON E5-1680 V2 be a worthwhile upgrade at this point? It looks like the best of the old X79 CPUs. It would give me 2 more cores / 4 more threads and sounds like it overclocks well, but not sure if it's just wasted money at the end of 2019?
These motherboards still have everything we need except maybe M.2 if I want to get larger M.2 SSDs instead of SATA, but with so many PCIe 3.0 lanes available, I think I could use a PCIe to M.2 adapter.

If I go the full upgrade route, AMD 3900X + mobo would be at least $700; would I need more than 32GB DDR4 RAM for $100-ish?
So total upgrade for ~$800?