No worries about the long message, the information is helpful. I also would like to cool things a bit more, and stumbling across your issue apparently will help me do just that since we have essentially identical situations as far as cooling is concerned.
For the drivers thing, if you have the time and inclination to do so, I refer you to the thread for it where I posted and have been deliberating with very helpful forum members: Intel GPU running and the NVIDIA one isn't (I think it's a hybrid graphics setup) - #48 by d-air1
Truth be told, we’ve kind of settled on the “reinstall is probably the best course,” but since I have to wait a couple of weeks for that, I’m holding out for some surprise troubleshooting help. You are welcome to see what we’ve tried and offer your input, but even if you don’t thank you for your explanation of the cooling business!