I have had a few discussions with a tech at Noctua.  Looking at the i7 7820X and an x299 motherboard.  Asked about the possibility of aircooling the 8 core processor.  Here is the correspondence...
 
Intel i7 7820X
Asus x299-A

I am a moderate (at best) overclocker.  My current i7 5820k is
overclocked to a stable 4.0 GHZ using a Cooler Master Hyper 212 EVO and
never exceeds 55C at full load.  I am more interested in your NH-U14S
for the new build.  Will I be able to maintain decent temperatures and
overclock to 4.0 GHZ using your cooler?  I don't want throttling.

Thanks
 
Here is Noctua's response...
 
Dear Bob,

first of all many thanks for your interest and your inquiry at Noctua!
We could only test with the 7900X but the behavior should be the same.
Unfortunately the new platform is not very overclocking friendly, due to the use of thermal paste instead of solder.

I've seen core temperature spreads of 15-20°C between the hottest and
coolest core, which is double what I've seen on Haswell-E before and
also higher than Broadwell-E.  Such spreads make it very difficult to
max out the CPU, even though SKL-X gives you the option to alter the
multiplier and voltage per each single core, so one can somewhat work
around it by fiddling around with the setting.

However, even with a D15, which is very similar to a U14S in raw
performance, I was unable to run 4GHz on all 10 cores with AVX workloads
(Prime) without reaching over 90°C on certain cores.

Prime is an extreme case and usually power consumption in real world applications is not as high, allowing higher clocks.

>From my experience: It could be possible with lots of fine tuning
but not in an easy "fire and forget" way, like it was with HSW-E, unless
you are lucky and end up with a very good processor.
 
Kind regards,
Andreas Karner
Noctua support team
 
 
The key here is thermal paste instead of solder...causing the fluctuations.  Even the 8 core is susceptible.  I was hoping that it was only the i9 series...Now having discussions about Threadripper and the reality of compatibility.   

Interesting, thanks for posting that info!
 
It makes me all the more curious if HCC silicon will be soldered or not, there is still a lot of debate over this. Going by the evidence in that email there's more than a few reasons Intel would use solder on HCC and larger parts. 

delid for the win
Is delidded+liquid metal better than soldering?

Wonder how effective the EVGA CLC280 would be here? 

Nicklas0912
He have no reason to test AVX load, as you would nerver ever get at load at 512 Bit AVX.
 
If he was useing the normal prime95 load, he would reache like 60-62C max.
 
AVX load kills everything.

Agreed, using AVX maxed for thermal testing is silly, you will never hit that load in real world usage, and AVX makes it run way hot.