Threadripper 2990wx, 2950x, or 1950x

I'm fishing for anyone's well-informed thoughts on the topic of which one of the TR processors noted in the topic would be best for chess engine analysis, as well as suggestions for a build, like those provided last year by Nunn when TR 1950x came out. Thank you.

Phoronix review of 2990wx check the results at the bottom of this page. At least under Linux the 2990wx has the lead. Under windows 10 there seem to be problems with thread affinity. Whether memory access speed limitation of the 2990wx in some applications is processor or OS related is an open question. Probably cache size of the 2990wx is sufficient for chess to compensate the missing memory channels compared to Epyx. 

Find more details about the windows 10 / 2990wx / memory bandwidth issue together with more chess related benchmark results at
windows-kernel-updates-may-be-required-to-optimize-for-threadripper-2990wx-cpus

Build:

Motherboard:
If you choose the 2990wx check 2990wx power consumption to evaluate your power requirements (depends whether you want to overclock). Without overclocking most X399 boards should provide the needed 250W for the cpu. Same holds if you choose the 2950x even if overclocked. The MSI X399 SLI PLUS is one of the cheapest and sufficient. Overclocking the 2990wx you can easily reach 500W, so the MSI MEG Creation - MSI MEG Creation review - is your friend if you want to prevent the VRMs from catching fire.

Power supply:
Depends on CPU power consumption + what GPU you use. For chess a passive cooled 30$ Nvidia 710 is sufficient, then a 800W platinum PSU like the corsair 760ax is ok. For some motherboards the PSU needs to provide two 8-pin CPU power cables (the 760ax does). If you overclock the 2990wx and have a 1080Ti a 1000W platinum PSU like the Corsair HX1000 is better suited.

RAM configuration:
Both 2990wx+2950x support 4 RAM channels, so you need >= 4 RAM modules. Don't even think about using only 2. Next priority is "dual ranked" which is much faster on threadripper. Finally try to get 3200 CL14 if possible, for instance the G.Skill [ RipjawsV ] Black DDR4-3200 CL14.

CPU cooling, case:
The case should be chosen depending on your cooling solution. For the 2950x and the non overclocked 2990wx I recommend the Noctua nh-u14s-tr4-sp3, but add a second NF-A15 PWM 140mm fan. Check if it (and the motherboard) fits in your case. The smallest case which fits this fan and the oversized EATX MSI MEG creation motherboard I found is the Corsair Carbide 400C I used for my build. Replace all case fans with Noctua ones if you want everything to keep quiet under load. Make sure you have at least two 140mm front fans and a good 120mm rear fan - like the Noctua NF-A12x25. Remove the HDD cage if not needed to improve the air flow.  But what to do if you want to overclock the 2990wx? The Enermax LiqTech TR4 360 seems the only solution, but it requires a bigger case, is plagued with corrosion issues and there will be a 2nd version out soon. I chose to stick with the Noctua u14s for now which means moderate overclocking - saves a lot of power too.

Hard disk, GPU
Has no influence on chess engine performance.

 I...I'm stunned.  Absolutely stunned.  Thank you so much.  Astonishingly gracious of you to share your expertise.  Thank you, again.

About the last generation:
Price/speed relation is not much better for the 1950x compared to the 2950x (yet) which makes it less attractive. The 1920x instead is heavily rebated now, see 1920x for 249$ (already sold out). It may be worth to watch out for special offers. The biggest advantage of the new generation, XFR2, is irrelevant if you plan to utilize all cores, which chess programs do.
You definitely want to manually overclock the 1920x and 1950x, there is no "built in overclock" when all cores are under load. Compared to the new generation you loose about 100-200 Mhz maximal clock rate (all cores) and you need about 0.05 V higher Vcore which leads to slightly higher power consumption. So if you feel comfortable playing with manual overclocking a highly rebated 1920x could be an interesting option.  Regarding build what I wrote about the 2950x above is also valid for the 1920x. Beside that you can use a weaker PSU (only 12 cores) and running your RAM at speed 3200 could be difficult, many last gen users buy 3000-RAM and run it at 2933.

Software:
To utilize the 2990wx for chess it seems necessary to use Linux at least as long as the windows scheduler issue is fixed. Linux/Windows chess performance indicates a significant windows performance penalty for stockfish. Disadvantage of Linux is that there is no Linux variant of the chessbase software. But as chess GUI we have Arena Arena Download which has a Linux binary distribution, and ScidVsPc ScidVsPC where you can download the sources ScidVsPc Download and compile it yourself which is as easy as typing "make" in a command window.
As engine I recommend brainfish https://www.chess.com/forum/view/general/how-to-install-brainfish-the-best-chess-program-in-the-world . You can download and compile the sources Brainfish Source from Zipproth . Don't forget to install the Cerebellum book.
Compile using "make profile-build ARCH=x86-64-bmi2" and check the speed of the resulting executable using "./stockfish bench 128 64 23". I got a compilation problem for "tt.cpp" file which I solved by using the corresponding file from the original stockfish source tree Stockfish Github . As Linux distribution I recommend Mint 19 Mint 19 Installation which is easy to use for windows users and comes with a modern gcc variant improving chess performance of the build.
A short addition: It seems cfish in Numa mode (which not yet works correctly in Linux for the 2990wx) works very well on Windows 10 using all 64 threads. No significant slowdown, seems faster than Stockfish on Linux.