Ukrainian language site Overclockers.ua found this nugget about the Intel Core i9-7900X Skylake X processor.

It needs to be comparied with the spec we were expecting 

The database entry SiSoft lits the processor ID as an "Intel i7-7900X CPU" but sometimes software needs to be updated with new ID references or parameters to get designated names correct. It shows that it runs at a base clock of 4GHz with Turbo Boost up to 4.5GHz on tap.

It shows the 1MB of L2 cache and 13.75MB of L3 cache in line with the previous leak. A slightly worrying spec not touched upon so far concerns the processor TDP. Previously it was touted as being a 140W processor but it is reported as a 175W CPU by SiSoft Sandra.

The motherboard supporting Intel's upcoming Skylake-X processor is a Gigabyte X299 AORUS Gaming 7. The X299 designator is the Intel chipset being introduced to support these new CPUs and platform features.