First off, welcome to the forums!
 
I have done SLI, 3 way SLI and SLI + PhysX before, I generally avoid cooling anything with air, but then again, im kinda OCD about keeping things REALLY cool.
 
Did you have questions regard this setup?  Are you looking to build?
 
If this is another "why PhysX" well, some PhysX titles do definitely benefit from it, but it all depends on your setup.  If you have 2 1080s and are playing on 1080p, even a solid PhysX title will not benefit, or at least benefit very little.  I recommend testing with NVidia's PhysX benchmark, test with and without your PhysX card and see the results for yourself.  http://www.geforce.com/wh...11-and-physx-benchmark
If you are unsure if the title(s) you play support PhysX, then you can also check here:  http://www.geforce.com/hardware/technology/physx/games
 
Feel free to ask any questions you like here, we will do what we can to help out.

Scarlet, correct, not on an FTW, I think I misunderstood the question then, I thought the OP was getting at "I sqaw SLI+PhysX listed on this board, who runs that kind of setup, and do you go air or water".  I might have been too quick to go there as I have seen a lot of questions in the last couple months regarding SLI+PhysX, how does it work, is it worth it, etc. 
Also I didn't say 3 way+PhysX, I said 3 way SLI and SLI+PhysX, it appears I forgot my oxford comma :p 
 
If you are wanting to run ANY tri-card setup on a Z170, either 3x SLI or SLI+PhysX, if you do not go water, which would be my recommendation, I STRONGLY recommend using Blowers.

Hi guys,

Question about 2 Way SLI + PhysX. How does that work exactly? Are the first 2 cards connected with 2way SLI bridge and 3rd one than assigned to physX? Or must all cards be connected via sli bridge?