The 1900x is really the chip that the 1800x should have been in the first place. Not so much for the 64 PCIe lanes. More than the 28 that are available in x370 is great but 64 lanes are not that essential given four way sli has pretty much gone away and other than graphics cards, nothing else uses x16 PCIe lanes.
Together with the extra 100Mhz of probable overclock headroom these should get, the key thing that will let this chip be properly performant in gaming/graphics loads will be the second 32 byte/cycle infinity fabric interconnect to the additional dual channel memory controller.
Having two interconnects to access system memory will mean that each memory controller only has 8 threads and 1/2 a GPU to support instead of the 16 thread and 1 gpu load R7 chips place on their memory controller. The 1600 and 1700 both perform about the same in most game benchmarks suggesting that 8-12 threads is about as much as a dual channel memory controller can comfortably handle in a gaming load.
I wonder how many reviewers will test the 1900x with memory only in dual channel mode and repeat the same ridiculous waffle that some of them said about Ryzen