Both great replies. However i have tried every pcie slot. And it's only after modding the bios of the cards.
Flash. No video
Reflash stock rom. Video.
Flash. No video
Reflash stock rom. Video

So yes. Right port. And i have tried every slot anyways

This is my only work around.
Keep one card unflashed stock
Flash other 5 cards

That way video works all the time
And i can adjust voltages with afterburner

Is anybody able to control volts with 6 modded cards on z170/z270 boards?