The new SKUs are not clocked slow either, the Ryzen 5 1600X six-core processor is clocked as fast as its bigger eight-core brother at a 3.6 GHz base clock and 4.0 GHz Turbo. The quad-core 1500X on its end has a base frequency at 3.5 GHz and 3.7 on that Turbo. Now, before we get into detail, under the hood (that would be a euphemism for heat-spreader) these processors are ALL 8-core parts (physically). Yet they have been sorted and reconfigured. That quad-core in reality is the 8-core part yet set up and enabled in a 2+2 fashion, thus each out of the two 4-core clusters (CCXs) has 2 cores enabled.
For the six-core parts that means per 4-core cluster (CCX) one core is disabled and that means these processors are set up in a 3+3 fashion. Other than that, again these are physically the 8-core Summit Ridge parts. That also invokes corresponding caches, TDPs and yes, these processors are all threaded and multiplier unlocked as well. The 1600X will have a 95W TDP, the 1500X sits at 65 Watts. According to AMD, Ryzen 5 1600X will be competing with the Intel Core i5 7600K and the Ryzen 5 1500X is attacking the price and performance bracket of the Core i5 7500. Link