So I solved one major problem. My psu from a well respected manufacturer, which was sent to me to replace another faulty one, has itself quit. It had been dribbling along simulating other problems as well as rebooting under heavy gpu loads, but finally failed to boot all together... so now it's all packed up and shipping off for RMA this morning.
Since the problem seemed to accelerate since I bought the M8 Hero I was concerned, but I'm very happy to finally lay the problem off to the psu instead, and the Hero is working just fine.
So glad to finally get that problem solved!