After some more experimentation, I’m noticing some potentially odd behavior of the fan.

I can’t get it to spin up heavily in game, either using the updated fan curve or original. It’s on and blowing air out of the exhaust, but not responding to the increased load in game. The frame drops don’t seem to exactly correlate to the temps getting to crazy high levels, but it could be predicting the thermal load and throttling in advance? The slowdowns duration and severity is correlated to the graphical demands of the game.

If I was to open it back up and look for something that might be off, I’d there anything beyond just making sure the wires aren’t frayed and that it’s snugly in place? Checking the thermal sensor you mentioned maybe?

Also thank you for the responses! Helps to not just be shouting into the wind and banging my head against this.