RTX 3080 undervolting not reducing power draw?

I am running my Ryzen 5 7600 and RTX 3080 off a Superflower Leadex III 550W. So when my GPU is under full load and drawing 360, 370W it gets pretty scary considering that's 2/3 of my PSU capacity.

But when I try the undervolt curve in the picture (850mV/1852MHz) and run 3DMark TimeSpy Demo and use MSI Afterburner to monitor the GPU core clock, voltage and power, the power draw remains the same at 360, 370W at 100% utilisation. I thought by reducing the clock speed and voltage below stock I can severely reduce the power draw. Am I doing something wrong?

I read that setting power limits is not advised as it can cause stutters at full load, so I'm not sure what else I can do.

These 2 videos from Optimum and Cynikaly show 100W lower power draw, why can't I achieve the same thing? Any advice is appreciated, thanks 🙏