I am trying to setup a 12 GPU rig with EVGA FTW3 1080 ti's with two 1600T2 PSUs, but running into the same problems with over the last day.

When booting up the rig with 2-3 cards in place i get Error: Invalid Device Ordinal

I initially began inserting GPUs from 1 to 13, but have also tried starting with the PCI-E x16 slot (slot 4) and then going top to bottom.  When I try this the monitor never shows the console data.

I had a similar problem on a different rig (Invalid Device Ordinal) when trying to add the 11th card, so I just let that rig run with 10 cards, which has been stable for 3 days.

Anyone running into this problems, and hopefully know how to fix.   Thanks.