Rivendreth obliterating my laptop!?!

First of all, if the fans only ramp up shortly before the machine shuts off due to thermal throttling, then the fan profile isn’t set correctly or proactively enough. You should be able to tweak that.

Each zone has different issues for cards - we see people complaining about Ardenweald, or bastion, or revendreth. You might want to check the thread about weird and varied graphics issues in revendreath.