The Ryzen Threadripper 1900X is US$50 more expensive than the Ryzen 7 1800X, and even though they have similar specs, the Threadripper CPU is worth the extra cost considering the benefits of the new X399 chipset.
https://www.notebookcheck.net/AMD-has-announced-the-US-549-Ryzen-Threadripper-1900X-octa-core-CPU.239662.0.html