The one not being picked up, is connected together with the motherboard on the psu?
No, it's connected to the other PSU which is only powering 3 cards, nothing else...
And it's weird because PCIE 1,3,4,5,6, are showing... What is labeled as PCIE2 is the 16x slot, but my monitor is plugged into that card but it's not showing as an active mining card...