Unless you use HDR…

I still experience 90W idle on the desktop if I enable HDR on my main 1440p75 monitor. 7900XTX.

It seems to be tied to the IO dies and memory speed. At normal idle both the GPU cores and memory I/O can clock down below 10mhz, but as soon as I turn HDR on, the memory becomes locked at a full 2450mhz and I get the high power draw.