Most of the times it's the risers fault
I guess the risers are powered, correct?
Try changing risers/GPUs to check them,
Also remove all of the GPUs and boot with one at a time
Thank you evakka for the reply! Finally someone is willing to engage in the solution! I am grateful for your troubleshoot at the solution but, I have already sequenced all GPUS through all risers and in turn through all 1x, 16x & mini PCIe slots. They all work perfectly solo, as one would expect. The issue I believe is that my mini PCIe shares the same lane with my PCIe 1x lane 3. Any ideas on that? The only other thread I could find on this was from 2013-2014 here:https://bitcointalk.org/index.php?topic=391411.0 I truly believe this can and should work but I am overlooking a piece of the puzzle here!?!?!