Only put the RAM you need in the box, use peripherals with working ASPM, attach them to the northbridge PCI ports instead of the CPU's root ports, use wireless instead of wired networking, and don't attach a display.

I do basically all of that, CPU idles around 5% but still consumes over 100W. (Minus the Wireless part)

(5800X + 64GB)

I can enable Eco Mode in the BIOS, which will bring down the CPU to about 65W max although its still at about 100W total system.

Chiplet based Ryzen CPUs inherently have higher idle power draw. Monolithic chips like 5600G have lower idle power draw. The motherboard, power supply, and internal peripherals all need to be carefully selected to get a really low idle figure.

Whatever software you are using is totally, utterly broken. Not sure what else I can tell you. Even a completely decked out Ryzen AI Max Pro 395 idles at 5W in Windows S0 (see: https://h20195.www2.hp.com/v2/getpdf.aspx/c09133726.pdf)

1W is a unicorn as just plugging in a power supply with no PC parts hooked up will register 1W. <10W is more realistic. Select a PC that can run off a laptop charger. Check manufacturer spec sheets for the idle power consumption. Don't install any PCIe cards or hard drives. Use powertop --autotune.

> Select a PC that can run off a laptop charger.

(looking at my 330W laptop charger)

I’m not sure that is the constraint you think it is.

To be more specific a 65W or 90W laptop power supply.