I built a i3 Plex server with trunas scale I bought 13th gen and trunas didn't recognize the i3 properly in beginning for hardware encoding. After digging around on some forums I was able to add in the hardware id somehow and got it function properly. I took awhile for me to find the information to make it happen and there's a possibility updates to truenas have added it in.
Before hw encoding was working right CPU would hit like 80-90% utilization when transcoding after getting it to work I see 20-30% max on transcode.
I use the Intel stock cooler and the CPU rarely ever gets over 40c in an 80f household.
I wish I could tell you the wattage but I don't think truenas interface has a CPU power monitor just temps. Which at idle is 35c in my chassis
I didn't want to do the conversion haha my thermostat is in Fahrenheit for the house