I had a disastrous day today.  I attempted to add a second PSU to my rig along with a RX480.  My rig was 3 r9 380x vid cards and a 750w power supply.  Well I fried my motherboard.  Which led me to having to get a new mobo, and cpu and memory (local fry's no longer carried lower end mobo that I was using).

Well I got everything hooked up, and the rig when only the RX 480 is hooked up runs just fine.  I cannot boot into ubuntu when even 1 of the r9 380x's is plugged into the mobo.  It just seems to hang.

Does anyone know if a 380x and rx 480 are not compatible?  It seems like they use the same drivers.  Not sure what is going on here. Do I just need to throw in the towel and ditch the 380x's and get more rx 480s?