Soldato
Could it be down to the VRM's getting too hot? I know MSI had problems in the past with overheating VRM's (I think it was their R9 280X Gaming card). I know the fans don't spin up until the GPU hits 60C with some cards, but chances are the VRM circuitry could be getting quite a bit hotter than that with no airflow, even if the GPU itself is just below 60C.
Hard to tell, mate. The fans go to 80% at 65C with my custom curve and I have 2 SP120 Performace fans blowing on the heat sink, so there's plenty air flow.
I know the power usage is viewable in AB and as soon as it hits 103% it throttles no matter what the core temp is.