I took a bit of time to fiddle with the BIOS setting you mentioned. None of them resulted in a lower TDP when idle, so the summary is:
- ~ 9W running idle, ~ 23 W under load, ~ 1.7W powered off.
So I took a look at the CPU Wattage in HWinfo, where I saw that the CPU was drawing 3 - 4W on idle. So I guess the power transformer might be inefficient. I tried other two supplies I had around (also cheap ones) and there was no difference. I've tried switching the NVMe with a SATA SSD and the TDP stayed pretty much the same. There was nothing else connected.
All this led me to another think I don't get. Take a look at the TDP of J4125, N5105 and N5100:
View attachment 25127
How can
the N5105 in this video get even below 4W? I ordered the N5100 instead of N5105 specifically for the lower TDP, and now I am quite buffled to see they behave pretty much inversely to my expectation