Question No diaplay when adding 3rd GPU. Help needed

[Jonyon]

have supermicro C9Z390-PGW motherboard, it has 4 PCI Express x16. I have 4 brand new Nvidia gtx2080 GPU's , the PSU is 1800W, When I connect 2 of tem every thing work flawlessly but when I'm adding the 3rd (and of course when i'm connecting also the 4th) there is no display at all. Its not even POST Do you what the problem could be? I've checked all cards separately and they working and alao the PCI Express ports working - also check every port with only one card in it each time I didnt install the drivers yet maybe this is the problem? But if so how it that with two cards windows boot (yes im running windows 10)
Ive also changed in the BIOS the 4g decoding to enable and I dont have the option of pci gen1

 

[rgd1101]

full system spec? include make and model of the psu

 

[Jonyon]

full system spec? include make and model of the psu

The PSU is Xigmatek X x-miner 1800w
Ram - 16gb DDR4
CPU intel i9 9900
HD toshiba SSD 256GB