Its black friday time and newegg has the processor i will one day own.
I was set on the 5820k for a long time but right now the 5930k is on sale and its only $85 more are the 12 extra pci-e lanes worth $85 the price difference while not on sale was not enough for me to justify but right now on sale its really temping.
To answer any potential questions right now I have only one GTX980 TI Will use a m.2 drive
I would go with the 5820k easier to overclock and cheaper. Unless you want a triple or quaf SLI/crossfire setup there really isn't a good reason spend the extra money. The cache is nice but with a healthy 4.5 to 4.7 GHZ overclock the performance becomes about the same.
I hadn't even considered any potential performance difference as I was just thinking of the M.2 NVMe storage expansion moving forward and even DX12 which may support mulit or even mixed GPU setups better. Personally if it wasn't going to cause me financial hardship I'd like the extra expansion potential. You'd need the physical slots in a mobo to use those lanes of course beyond just GPUs as some of the cheaper boards would be more limited.
If you've got a 980 ti plus an M.2 drive, as you said in your original post, the 5820K will be plenty. Even if you then upgrade to tri-SLI (x8 x8 x8), you will be fine. Only if you anticipate going quad or getting crazy with a bunch of other PCIe devices in the near future would I personally consider the 5930K. Buy based upon what you need now and in the near future; historically, Intel HEDT chips have held their value pretty well, so if you decide in two years that you absolutely need quad-SLI and loads of PCIe storage, sell it and upgrade to a chip with more lanes, which will likely be better and/or cheaper than the 5930K is now anyway.
One question: it's your first build, and you're using Sata Express drives? May I ask why? The jury is still out, but all signs at the moment point to SEx as being DOA. I personally would stick with M.2 or normal PCIe slot devices, and avoid SEx. Abstinence, kids!
Just thinking aloud but the HBM2 GPUs are only round the corner, Intel's 3D XPoint storage is appearing next year in some form. Personally I've got 3 SSDs in my system, HDDs are long gone and SATA is rapidly following suit in my next major upgrade!
All potentially high speed devices fighting for those PCIE lanes so something for the OP to consider. I don't know enough about them to know exactly what they will require interface wise. Interesting times regardless.