When life gives you lemons (broken CPUs), you make lemonade (idle power usage measurements)!
Unfortunately, it’s exactly as I predicted: The AMD Ryzen 9 9950X3D consumes 10-15W more power in idle (also active idle) compared to the Intel Core Ultra 9 285K.
The 12900K measurement is an entirely different machine, the 285K vs. 9950X3D measurement was done in this machine (only swapping Mainboard and CPU): https://michael.stapelberg.ch/posts/2025-05-15-my-2025-high-end-linux-pc/
In practice, I need a working CPU, so AMD it is, I guess, but… :(