This is the problem, if I boot up with one card , in the pcie1 ( the only  16 pin pcie on the motherboard , and as intruction on the motherboard says , the first one that i have to install) the computer wil start , the fans also but i have a black screen. And this happens only when i have a card plugged in this pcie1.

Hello!

I would greatly appreciate your help!
I have just assembled a mining rig with these specs:

H110 Pro BTC +
2× PSU Bequiet! Dark power Pro 1200W ,connected between them with Add2Psu
6× Nvidia Aorus 1080Ti Extreme
Intel Core i3 -7100 CPU
16 GB RAM
Windows 10 Home with the latest upgrades

The first problem that i've met was that the computer was not booting up with any of the gpu connected to the pci1( x16), so i decided to start from the second pci. With them connected in these manner and following the instructions of the motherboard , i've installed them all, but now every time, i start mining the sistem freezes or crashes. Sometimes it takes 5 minutes and never stays online more than 2 hours.

Thank you a lot , comunity!