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?
Figured out my problem. My risers were fried too. And one of my 380x's. Have 2 380x and rx480 mining now. Have a new r9 Fury arriving Wednesday...
RUN THE 300 SERIES CARDS TOGETHER--
Three 380X cards are enough to break a 750W PSU. The 400 series cards are not so compatible with earlier cards, and require AMD 16+ drivers. In my experience, 300 series cards mine more slowly on AMD 16+ drivers. I have read that 300 and 400 series cards can be mixed on AMD 16+ drivers, but I don't have a rig configured like that. R9 Fury cards mine really well mixed with 200 or 300 series cards, but the RX card should be kept with other RX cards.
Sorry to hear about your motherboard, but I would double-triple check it and the CPU before tossing it. BAD RISERS are a very common problem, and enough to prevent booting. --scryptr