Suggestions on this rig

I’m about to pull the trigger on this build and I just wanted your opinion.

CPU - Threadripper 1950x
AIO - Corsair H115i
Mobo - Asus Zenith Extreme
RAM - G.Skill Trident Z 32GB (16GBx2) 3200Mhz
GPU - 2x GTX 1080ti FE
PSU - Corsair 1200i
SSD - Samsung 960 PRO M.2

My first question is regarding the RAM, should I get 4x8GB and get quad channel going or just keep the 16GBx2 and add the other 2 later? Would quad channel work that way?
The other question is regarding the PSU, I plan on adding 2 more GTX 1080ti FE during next year, I’m sure the PSU won’t be enough. What’s a good PSU that can handle 4 GPU’s plus a Threadripper?
Cheers guys

I forgot to mention that this is a Workstation, that I will be using the mine.
Also, this will be on a case, not a open air. Thanks!

If you add more GPU you need 1600w and you not need ram 3200mhz if you use 3D max, Cad app Mhz not matter waste you money.