Intels new HEDT (LGA 2066, Skylake-X, Kaby Lake-X)

So, Intel revealed at Computex their new LGA 2066 -platform and CPUs to accompany it.
And it's a mess.

Kaby Lake-X are the exact same as Kaby Lakes only fitted for LGA 2066 instead of LGA 1151, and iGPU fused off (but still on silicon).
They support 2 memory channels, so 2-4 slots (depending on if the motherboard has 4 or 8 slots) per motherboard apparently won't work at all.
They support 16 PCIe lanes, so some of the PCIe slots won't apparently work either.

Skylake-X is split into two: LCC aka Low Core Count and HCC aka High Core Count.
LCC's are 6 to 12 cores, 4 memory channels and 28 PCIe lanes for 6- and 8-core models, 44 for 10- and 12-cores. Intel hasn't specified 12-core versions clocks, caches or TDP yet. Intel hasn't specified release dates for all of the models yet apparently either (6-10 cores Q2, no word about 12-core)
HCC's are 14 to 18 cores, 4 memory channels and 44 PCIe lanes. Intel hasn't specified any clocks, TDP, release dates or anything for any of the models yet. Asus rep slipped that 18-core version won't actually be even released until next year. edit: ASUS rep has edited his post to say "later this year" instead. https://rog.asus.com/forum/showthread.php?93632-Late-June&p=653561&viewfull=1#post653561

LGA 2066 platform has great new feature: Bootable NVMe RAID from the CPU.
Except that it's only RAID 0 by default. Getting RAID 1 and 10 means you have to buy physical key which costs $99. Getting RAID 5 means getting another physical key which costs around $300. And you actually need Intel-branded NVMe SSDs for it to work at all.

Video with lot of the same info:


edit: fixed small mistakes I made tired last night

 

Motherboards assign certain slots to certain channels
X299 has Channels 0/1/2/3 and 1 or 2 slots for each channel (depending on if there's 4 or 8 slots total).
With Kaby Lake-X you can fill Channel 0 & 1 slots, with Skylake-X you can fill all 4 channels.

Z170 has Channels 0/1 and 1 or 2 slots for each channel (depending on if there's 2 or 4 slots total).
If you put all your DIMMs in Channel 0 or 1 you'll run in single channel mode, if you put DIMMs in both channel slots you'll run dual channel mode.
(and same for X299, if you have 8 slots and put in only 2 DIMMs and place them both in Channel 0 slots, you'll run in single channel mode etc)

 

They both support 2 DIMMs per channel, so 4 and 8, but it's also about the motherboard - the motherboard has 4 channels and 1 or 2 slots per channel, with Kaby Lake-X half of the slots simply won't work

 

Intel engineer gave interview about the new Basin Falls -platform

 

as @tunafish said, 4 dimms if the motherboard has 8 slots. If the motherboard has 4 slots, you only have 1 slot per channel and thus can use only 2 dimms on kaby-x

 

No you wouldn't, you could have dual channel with Kaby Lake-X (channels 0 & 1) and quad channel with Skylake-X (channels 0, 1, 2 & 3)
Motherboard designed for 2 memory channels and 4 slots (for example Z270+Kaby Lake):
Channel 0 | Channel 0 | Channel 1 | Channel 1 (this is why with 2 DIMMs you leave 1 slot in between them - also there could be mobos where it goes 0101 but they're rare these days, if not extinct)
Motherboard designed for 4 memory channnels and 4 slots (for example X299 with 4 slots)
Channel 0 | Channel 1 | Channel 2 | Channel 3
Motherboard designed for 4 memory channnels and 8 slots (for example X299 with 8 slots)
Channel 0 | Channel 1 | Channel 2 | Channel 3 | Channel 0 | Channel 1 | Channel 2 | Channel 3

Kaby Lake-X can use channels 0 and 1, Skylake-X channels 0, 1, 2 and 3