Hello. I have same motherboard, I switched two of these, I have the problem with 2nd, pci-e 16x slot... not working for me.
Even if I put graphics card directly into that slot, and put in bios that it's main display, it won't show the display... and will not register it.
I bought two of these mobos thinking that first one had problem with slot but no.
I have 1070 strix. 5 of them working perfectly but the middle big slot no. I thought it was power but no...

See, even I put out from left 1st pci to 2nd, not working.. I tried all combinations and nothing. Does anyone have any idea what it might be?

Before this I used ASROCK h110 all 6 worked fine but mobo died.

I am running.
6x 1070 GTX Strix.
Antec Platinum HCP 1300 W
GA-Z270P-D3
SSD Intel M2 256GB
i7 7700k 4.2ghz
8GB RAM 2400 MHZ


Would like to hear any recommendation what should I do. I wasted kind of another 100e for second one. I was 10000%ish sure that it was PCI slot broken....

Thanks in advance.
Alex.