X299: it should work
The new 12- to 18-core Core i9 processors have to be paired with the same Socket 2066 motherboards as the existing Skylake-X processors. By this we mean motherboards with the Intel X299 chipset. Nevertheless we are kind of wary, considering the voltage regulator modules on some X299 boards can get extremely hot even when using a 10-core CPU. In June we published an article about a motherboard where we measured temperatures of more than 100 degrees Celsius when overclocking a Core i9 7900X to 4.5 GHz. The question remains what will happen when you use a CPU with double the amount of cores.
However, Intel states without reservation that all Intel X299 motherboards should be suited for the new CPUs. Considering the fact that we received our test processors in our test lab last Friday, we have not yet been able to run extensive verification tests. What we do know is that Intel released a new microcode for CPUs (put into the latest BIOS-versions of most X299 boards) which definitely reduced the idle power consumption of the chips considerably. Nevertheless, manufacturers presumably saw what was coming: after the launch of Skylake-X most brands released refreshes of their X299-boards with better VRM cooling. For example, the ASUS ROG Strix X299-E Gaming was quickly replaced by the ASUS ROG Strix X299-XE Gaming.
Anyway, if you want to use a Skylake-X CPU with a lot of cores and are also looking to overclock said processor, we can definitely recommend you choose a board with above average power supply and not one of the cheapest X299-boards. If you spend 2000 dollars on a processor, a slightly more expensive motherboard should not be a problem.
Important to note is that the X299-motherboards do not offer support for ECC-memory (with integrated error-correcting). For Intel this remains reserved for the Xeon server- and workstation platforms. AMD Threadripper on the other hand does support ECC.