It seems there was a bit of a mix up about the Intel Core i7 7740K and Core i5 7640K processors. When French magazine CanardPC wrote about these chips earlier this week it was assumed these were LGA1151 processors but now CanardPC got its hands on an engineering sample and it turns out it's actually a LGA2066 chip. So these processors are not part of the Kaby Lake-S lineup but belong to the Kaby Lake-X series and require a motherboard with the X299 chipset.
CanardPC received the following CPU-Z screenshot from its anonymous source. The tool incorrectly identifies the chip as LGA1151 because the CPU-Z doesn't properly recognizes the chip's package ID. This LGA2066 chip is an early engineering sample of a quad-core, eight-threaded processor, it runs at 3.3GHz, has a 3.5GHz Turbo, has a 112W TDP and supports dual-channel DDR4-2400 memory.
Intel came up with the 7740K and 7640K to fight Ryzen but it seems we shouldn't expect too much from it as it's basically just a further evolution of the 14nm Skylake for the chip giant's expensive enthusiast platform. Here's an overview of what we learned so far about the specifications of these two processors:
Intel Core i7 7740K
A quad-core processor with a 4.3GHz base frequency, 4.50GHz Turbo, Hyper-Threading, 8MB L3 cache and 112W TDP. The base frequency is 100MHz higher than the 7700K but whereas the latter can do just 4.4GHz with all four cores activated, the 7740K will offer 4.5GHz Turbo on all four cores.
Intel Core i5 7640K
This is a quad-core model with a 4.0GHz base clock but it's not certain if this model has Hyper-Threading or not. Leaked internal documents from Intel indicate it has no Hyper-Threading but these are not always reliable. CanardPC says they will know for sure once they can source a compatible motherboard for their engineering sample. The Turbo mode of the 7640K is disappointing, it's 4.2GHz when a single core is activated and 4.1GHz for two cores. The maximum Turbo for all four cores is 4.0GHz, so basically the base frequency of the 7640K. Just like the 7740K, this model has a 112W TDP.
German tech site PC Games Hardware confirms a lot of this and adds some extra details. The site says these processors will lack integrated graphics and hints at a release date near Gamecom in August 2017.