As reported by Videocardz.com, the Core i7-7740K is a quad-core CPU, with Intel Hyper-Threading, which uses a new socket LGA2066 motherboard, based on X299 chipset. It also lacks the integrated GPU, has a 3.4GHz base and 4.5GHz Turbo clock and a 112W TDP.
The CPU was spotted in the SiSoft database, running on the yet to be released ASRock X299 Professional Gaming i7 motherboard and pushes a score similar to the Ryzen 5 1600 SKU, at least in that benchmark software.
Bear in mind that Kaby Lake-X is just the tip of the upcoming Intel HEDT iceberg which will use an X299 chipset based motherboard as Intel has plans for the Skylake-X lineup with 6-, 8- and 10-core SKUs. The Skylake-X SKUs will have more PCIe lanes as well as quad-channel memory support.
As rumored earlier, Intel's Kaby Lake-X and Skylake-X CPUs are scheduled to launch sometime in Q3 2017, but now it appears that Intel could launch the lineup even earlier, in order to counter AMD's Ryzen threat.