Help!

So I got an 8 card rig but only 4 GPU's ever show up when I boot it up, recently I tried to fix it and now it only sees 2 GPUs, I am using a 850w PSU and a 1200w server PSU in conjunction but I have the risers powered by the server PSU as I don't have enough sata connectors for them all, can anyone help me troubleshoot why I am not seeing all my GPU'S? I have tried a lot of things but nothing seems to work.