Best guess is each claymore version uses more and more power.  v7 vs v6 for rx470/480 uses 15% more power or so.  so you just went over the edge of what your motherboard could supply to your gpu's, and it was too much.  thats my guess.  so yes, the software caused the problem - B U T - it was an unsafe setup from the start and you didnt notice anything because the power draw want high enough.  good luck !