Okay, not sure if it was the heat causing the red screens (as there were no signs of visual artefacts or crashes other than the entire system RSoD lockups), but I've since reversed the H80 to load the heat from out the back of the case instead of drawing cool air from there and dumping the heat into the case. Turns out it makes a massive difference for component temperatures while paying a tiny CPU temp penalty (who cares when the unit is already so damn efficient).
So far so good, and my temps haven't broken 80 yet let alone the 90s I was getting before. I've also made a custom fan curve since the stock settings never even hit 100% for some reason (these cards are whisper quiet anyways)
As for "throttling", highly doubt it as these puppies are easily pushing 1280 instead of the advertised 1137... I have yet to see a sign of lowered performance... these things are beasts 😄