Coffee Lake processor availability has been poor, even now weeks after its launch. As to why it is so poor, Intel doesn't shed a word. However, they will increase Coffee lake production by using a newly opened fab. Starting December 15th the volume availability would be better.

The Core i7-8700K, i7-8700, i5-8600K and i5-8400 will then be produced at the Chinese Chengdu. Intel issued a product change notification in which it states that fact. Intel states there will be no differences between the CPUs in terms of quality. 

Coffee Lake has been launched back in August, the first consumer mainstream parts with up to 6 cores have been an answer towards AMD A Ryzen series 5 and 6 processors. Check out our Coffee Lake 8700k review here and our 8600k review here.