What’s funny is that I went from the RM850x to an EVGA 1200 P2 to try to solve similar issues many months ago. Definitely seems to have helped. If I remember correctly, it was the 12v rail to the 3080 on the 850 which had some bad spikes when I checked it with my scope. The 1200 is better but still has spikes under load, but just not as bad.
Headroom is usually a good thing. As an engineer, I typically go big for a prototype or one-off, like my flight sim rig. If you have to make 10,000 of them, you find the minimum acceptable. I only want one. 