nVidia gtx
I have a question about cards 
Better is to buy some basic FE version or factory over clocked and then boost again with water collers? 

I saw somewhere not FE version but Oc gtx 1080 with temp 50c and clocked to 2134 mHz, ofcourse also with water collers
I wouldn't mess with liquid cooling. Go with the founders edition cards and save yourself the trouble. If you need to stack them back to back, be sure to remove the back panel of the cards that are affecting the air intake fan of the one next to it.
(04-10-2017, 02:19 PM)tacohashcat Wrote: I wouldn't mess with liquid cooling.

We can speed up card giving 300 mHz up and have stable card with temp 50c for example
I have seen too many liquid coolant pumps fail, causing more issues than if an air cooler had failed.
I have also seen liquid cooling burst, destroying all components in its path. Granted, these were not the highest quality products, but I have become a bit biased against liquid.
The only liquid cooling I would consider is immersion in mineral oil. https://www.pugetsystems.com/submerged.php