This is definitely the most overkill system I've ever built. I needed something that could handle heavy multi-threaded workloads but also wanted to use it for 4K gaming. I settled on the X399 platform since threadripper is great at highly threaded workloads. I mainly use it for discrete element modelling and processing astrophotography images. This processor is significantly more adept in these situations than my previous 5th gen i7. I went with the 2970WX over the 2990WX mainly because of cost. Micocenter had a significant discount on the 2970; it was half the cost of the 2990.
The only downside is that threadripper can lag behind in lightly threaded workloads like gaming. I figured that since I would be gaming at 4K, it wouldn't be too noticeable since you are usually gpu bound at that resolution. However, I was surprised to discover that I am cpu bound on some games like Shadow of the TR at high settings. Frame rates are still 100+, but even that apparently cannot saturate two 2080 ti cards at 4K with a TR cpu. It's close though, worst case has been about 85-90% usage on both cards, so I'm not too bothered by it.
After adjusting the timings, I was able to get a stable overclock on the ram at 3330Mhz and the dynamic boost enhancement in the bios consistently turbo's several cores to 4.2GHz. The small ram overclock actually caused a huge 2000pt difference in Time Spy. I assume that benchmark must be very sensitive to memory bottlenecks since Cinebench showed almost no change.
Overall, I think everything worked out pretty well and graphically intensive games look amazing. I fired up the witcher 3 and couldn't believe the visual fidelity coupled with how smooth everything was. I know most people are against 4K gaming, but after building this, I don't think I would ever want anything less.