I have just ordered the parts for this.
I changed my mind about stuff looking like this. See later reply.
ASUS PRIME Z270-P Mainboard
Core I5 7500 3,4GHz Int HD 630 65w CPU
64GB RAM 4x16GB HyperX FURY DDR4 DIMM 288-PIN 2666 MHz / PC4-21300 CL16 1.2V
1x Intel SSD NVMe 660p 1TB Storage
1x Intel SSD NVMe 660p 2TB Storage
Cooler Master MasterWatt 750 Powersupply
Cooler Master CM Storm Enforcer Case
LG BH16NS55 BDXL Writer
About 1312 US$ in all
From my current setup I will use:
GTX 1070 8GB
GTX 970 4GB (Keeping that in my old system)
HDD docking station
The external hardware.
64GB ram is because I do video editing, 3D modeling and are beginning to dip my toes in 3D animation.
I am going from 32GB and a FX8350, mostly because the I5 7500 offers hardware support for my chosen video editor. CUDA support was lost when Nvidia deprecated NCUVID.
I was considering going separate Win 8.1 and Win 10 machines, but with all of my external hardware it would be another 400 to 600 US$ for switch boxes.
So I will continue with a dualboot system and save that dough for later upgrades.
Later CPU upgrade
Core I7 7700 3,6–4,2GHz Int HD 630 or Core I7 7700K 3,6-4,2GHzInt HD 630
And further on, a better graphics card and a VR headset.
Now to settle in and wait.