I don't want to influence your component choice at all. Anyway, just a few recommendations from my side.
To have 100% compatibility with my guide (incl. BIOS settings) and my EFI-Folder distribution, I would still stay with the ASUS Prime X299 Deluxe, even if you do not need the TBEX 3 (you can sell it if you don't need it). If you opt for any other motherboard, please be ware that you also have to take responsibility to account for deviations from with my guide (incl. BIOS settings) and my EFI-Folder distribution.
To drive your GTX 1050 with 3 screens, you will probably have to enable CSM in the BIOS and add CsmVideoDXE-64.efi to /EFI/Clover/kexts/Other/.. Something I don't like at all and I only recommend if there is no other alternative. Do you really need CUDA? Else I would rather opt for a natively implemented ATI Sapphire RX Vega 64 (8GB) or at least for the Sapphire RX 580 Pulse (8GB).
Also think about one of the recommended BT/WIFI solutions. Onboard WIFI of most of the X299 motherboards will be useless.
The i9-7960X, certainly would be a good decision, as any i9-79xx is.... (stay away from i7 CPUs - only 28 PCIe lanes!)
Regarding DDR4, proof that the envisaged memory is compatible with your motherboard. I would opt for DDR4 =/> 3200 MHz, if possible.
Think about some adequate CPU water blocking.. minimum recommendation for all i9-79xx without OC: Corsair H150i
PSU: 860W-1500W
Good luck and have fun,
KGP
Thanks so much for your insight, I wasn't expecting this much help.
Of course the whole point is using the same MB you worked so hard on otherwise it doesn't make much sense.
With the TDP of these processors it makes sense to go with a high end MB and not skimp.
Indeed I could sell the TB3 card , hadn't thought about that.
I'll go with the Sapphire RX580 if that's what you recommend , I have no need for Cuda and my graphic needs are low.
Wifi I can do without and Bluetooth as well.
So 7960x/ Prime x299 Deluxe / RX580 / Seasonic Prime 1300 Gold / 32G Trident Z DDR4 Ram /Corsair 750D Case/ Samsung SSD 960 PCIe M2/ EKWB EK KIT X360 all just over 4K, the price I can sell my dual Xeon hack for.
It's a tough decision because the Xeons have served me well despite nagging USB problems but the low clock (2.2Ghz) is really a problem in certain situations.
I was initially intrigued by pastrychef's 8700k build as it was straightforward and worked first time. It overclocks easy on air but then I realised that geekbench only tells half the story and that DAWbench shows very different numbers for my specific use. I made the same mistake with the 2x44 core Xeons , not choosing the right CPU for the application.
I'll post back when it's done and tested, hopefully without any more nagging.
Thanks again, this build is thorough and inspiring.