Intel Core i7 8th Generation-core based on the Coffee Lake microarchitecture were introduced in early 2018. Those parts offer are manufactured on Intel’s third generation 14 nm++ process which allowed for higher clock frequencies.
Intel Core i7 Coffee Lake-based Core i7s were introduced in late 2017 with a number of high-end SKUs. A larger number of SKUs were introduced in April 2018. Although they still use standard Socket LGA-1151, those parts are no longer backwards compatible with earlier 100/200-series chipsets and must be paired with an appropriate 300-series chipset. A significant configuration change has taken place with the introduction of Coffee Lake including bumping the core count for the Core i7s from 4 cores to 6 and appropriately increasing the L3 cache which has significantly increased the performance of those parts over the prior generation