Intel finally expanded the core count of its mainstream processors, facilitating solid all-around performance from the Core i7-8700K. Aggressive Turbo Boost bins ensure great performance in lightly-threaded workloads, while six cores cut through demanding tasks much more adeptly than Core i7-7700K. Intel’s Core i7 line-up is still expensive, but you’ll pay a lot less per core than in prior generations.
Read more @ Tom’s Hardware
All these new processors are desktop parts, meaning they are socketed processors for use in appropriate motherboards featuring the Z370 chipset. Technically these processors use the LGA1151 socket, which is also used by the 6th Generation and 7th Generation processors with the Z170 and Z270 chipsets. However due to differences in the pin-layout of these two sets of processors, 8th Gen will only work in Z370 boards and there is no level of cross compatibility. We will discuss this later.
Read more @ AnandTech