7 GPUs cannot be found

I can find 6 after hours of troubleshooting this is what ive come up with.
My computer will detect 6 GPUS if the first pci slot is not connected. Connecting to the first pci slot my computer only detects 5 GPUS. I cannot get it to detected 7 GPUS when I have all 7 slots connected. Is it a bad slot or a setting in bios I'm missing?

I'm using windows 10 64 bit
Z170A Pro Carbon
RX 580 8GB