Looks like it’s a success, at least partially. I can burn in now for 30 minutes and the cards peak temps average out to around 85°C.
I say partially however because the cards aren’t reducing their power budgets, but they are throttling a little bit (around 170 TFLOPS compared to 200 TFLOPS when cool). I can live with that, but the fan in question is super loud. That said, finding the right fan (or setting a quieter curve) is definitely a more tractable problem.
Thanks heaps!
PS: Let’s maybe not talk about the cardboard box partial I/O shield. The used board came with an incorrect shield, and the replacement that I ordered seems to have been lost in transit.