I had overheating concerns with my RTX3070 (90-93c sometimes) and did a LOT of searching the web on this very setting. Many threads on other sites (Reddit, NVidia, hardware sites, etc) warned not to set this to Maximum Performance because of overheating concerns. They may not be correct, but there was enough of a split opinion on the subject that I decided to err on the side of caution and set it to Normal and check the results. I noticed no difference, so now I keep it at Normal and still use Ultra settings.
As info though, I did an online chat with nVidia and asked what my max temp was, and the tech said it was about 92-93c and that if it reached that high, it would either shut off or reduce performance accordingly. Yeah, I should have asked about the setting, but I forgot. 