Intel's previous generation processors, code named Kaby Lake, weren't much of an improvement on the desktop side compared to Skylake before it. In fact, Kaby Lake desktop CPUs were essentially factory overclocked Skylake chips. Now Intel is introducing the latest generation of their Core processors for desktops, Coffee Lake, featuring more cores and launching October 5th.
Leading the pack of these new processors is of course the i7-8700K (bulk order price: $359). The new flagship i7 now has 6 cores and 12 threads, up from the 4/8 it's been for many years. It's now a 95W TDP part, but even with a 4W TDP bump Intel had to make another trade off for the additional cores by dropping the base clock to 3.7GHz from the 4.2GHz of the i7-7700K. The new i7 is able to boost up to 4.7GHz, and has 12MB of L3 cache. Intel claims it'll provide up to 25% more frames per second in games compared to the 7700K, and be up to 2x faster than a three year old PC (so Broadwell) when "mega-tasking" (gaming+streaming+recording). The non-overclockable 65W i7-8700 ($303) is a little slower with a base clock of 3.2GHz and a boost of 4.6GHz.
The mid-range i5-8600K ($257) is also getting two more cores, bringing it up to 6, but still lacks hyperthreading. Base clock speed drops only 200MHz from Kaby Lake, now 3.6GHz and boosts up to 4.3GHz. This 95W CPU as well as the 65W i5-8400 ($182) have 9MB of cache. The later's clock speed is much slower at only 2.8GHz base frequency and a 4GHz boost.
The i3-8350K ($168) might be the most interesting of them all, believe it or not. This desktop i3 part now has 4 cores and a clock speed of 4GHz. It doesn't have Intel's Turbo Boost feature, nor is it hyperthreaded like its Kaby Lake predecessor. That being said, 4 cores at 4GHz is just right for playing AAA games at higher settings these days. With a 91W TDP and being unlocked by Intel, it should overclock decently for anyone that wants to squeeze out a little more power. The i3-8100 ($117) 65W variant's clock speed it locked at 3.6GHz, and both i3s have 6MB of cache.