Check your risers they be burned.
are you sure that "burned raiser" is not an urban legend?
bad molex contacts is something I encounter very often, but actually burned raiser is something that I haven't seen yet, but then maybe I'm just that good

Yeah I had a burned molex (peripheral cables)... It actually burned out on the PSU itself and damaged one of my outputs. Have just ordered a new cable from corsair and used a different output... What could have caused this? Can I do anything to prevent it? Could a claim be made vs corsair for warranty on my 1200w PSU?