Well shit, ok it's been going fine all night at stock settings.
But I will crank up the oc and monitor the temp and see if I can decect which one is crashing. Doing one riser at a time sounds like a pain. Although yeah I know one at a time is always how to diagnose stuff. I never would've thought a riser or something went to shit that wasn't even on my radar as a possibility.
I've had them fail in the past but it was obvious as the power cable melted or something showed signs of burning or melting