Opnsense idle power consumption 2X that of windows for the same hardware?

[superczar]

I had been running opnsense virtualized for the past several months and finally decided it deserves a dedicated hardware unit of its own.

I decided to redeploy an old HP SFF with i5-6500t that was being used as a desktop for this.
The hardware HP 800G4 with i5-6500t / 8GB RAB and a 256GB SATA disk.

While running windows , the unit used to idle at 14-16W most of the time (as measured by a reasonably accurate kill-a-watt meter on the wall plug) 

After installing opnsense 23.7, i enabled Power-D and set states to adaptive.
However the unit now seems to draw 28-35W all the time.
The use case is for a home and the CPU utilization is 3-5% most of the time which is about the same as windows idle.
There are no CPU intensive packages on the system and IDS etc is disabled.
The only additional plugin installed is wireguard although no inbound VPN connections were on during testing.
 
Power is expensive in the region I live in (about 20 US cents per kwh) and any opportunity to optimize it is welcome.
Even technically, I am surprised why FreeBSD/ Opnsense is drawing 2X power for the same CPU utilization.

Any suggestions or pointers?

[karlson2k]

Try disabling Power-D.
I my case I got lower temperatures and lower power consumption.

Looks like the kernel / firmware is managing CPU better than Power-D.