would depend which cpu you use, the kaby lake ones are 16 lanes, the next up is like 28 then 44

So you will have 44 pcie lanes to work with. Without knowing the exact way the lanes are divided up it would be 16x16 with 8 left over, so you could in theory run sli with x8 left for a third card or use that port/lanes for a super fast pcie ssd setup. Maybe one of the m.2 ports run off those. Until evga releases the specs its anyones guess but sli at x16 on both should be a given.

ypsylon
If you look at larger picture of said board you can clearly see slot lane speed
 
1. x4
2. x16/x8
3. x8
4. x8
5. x16/x8
6. x1
 
I hope it answers your question.

Where's the picture you could see that in? All the ones I've seen are too low-res.

ypsylon
Literally first on the list after using search engine. Go to WCCF website - direct link below.
 
http://cdn.wccftech.com/wp-content/uploads/2017/05/EVGA-X299-FTW-K-Motherboard.png 

No offense but they have horrible credibility. 

ypsylon
Give me a break. Not talking about WCCF credibility (99% of websites belong to 'doubtful' category BTW), but about official EVGA photo from Computex PR. Its not my fault that WCCF published better photos than others; oh wait they photoshoped it on purpose just to fool me?! Dang I'm such gullible being... 
 
If you won't believe that, who am I to force you to do so?

I was speaking in general.  I did say don't take it personal and you did.  

bdary
You can zoom in on the pic of the FTW-K here and see the slot speeds  >>  https://www.evga.com/articles/01114/
Looks to me like what ypsylon posted above is what EVGA's pic shows as well.

That's my original problem; those pictures on their news release don't link to higher res ones.

Iamrogue
can you find me on this picture where is RGB out for some not integrated lights?

from what i can see there are only three spots for rgb headers and they have connections on them for the onboard lights, one is in the bottom right, left middle and left top. there is a header above the top one but cant make out what the words say by it. but since it does have rgb fan header support im thinking the top one is the one. 
on a side not i did see the VROC connector on the bottom next to the usb 2 headers.

Will using the M.2 slots force any of the x16 slots to run at x8?

Ravenmaster
Will using the M.2 slots force any of the x16 slots to run at x8?

its really going to depend on which cpu you go with and were the m.2 slot gets its lanes from. if you use one of the 16 pcie lane cpu's then well you can see there will be a issue. if you use one of the 28 lane ones then you can see you still will lose some, with the 44 ones then not so much. now this is assuming the m.2 is coming off the cpu lanes and not the x299 chip lanes.