Considering how long I "hope" this machine will last I will take the modern hardware with lower power consumption.
Indeed. I'm seriously considering starting to replace more of my old hardware that is doing server duty with Ryzen setups just for the power savings. (Especially if I can find a good supply of some reasonably priced unbuffered ECC DDR4.) Even with our power cost usually down in the 3-6 cent per kWh my monthly power for the servers here is over $200 / mo, and if power spikes up to 10-12+ cents that's a significant chunk of change, even just for a month or two long spike in the rate. (I just pay the market rate and take my chances...
Overall it is cheaper than power plan options in the long run with an essentially fixed load.)
The power consumption at idle of the last desktop Ryzen setup I tested it on (I think that was one of the 2400Gs with a single SSD and a DVD burner, using only internal GPU and a good PSU) was only a few watts. Not even worth trying to set the thing to use the "sleep" modes to save power. The fans stop spinning at idle anyway and the CPU is so power efficient at idle that it's just not necessary, they throttle themselves down to virtually nothing anyway.
I actually had problems with the first 2400G system I built since it ran FreeBSD. While you would never notice it if it were a Windows box since it would never get
that idle, it would crash if you left it idle for long enough, like overnight at a prompt after recompiling the whole OS, it would just be frozen in the morning because the PSU didn't keep the power clean enough at no load. ASUS actually had to add an option in the BIOS to tell it to NOT go into the deepest powersave state to intentionally make it draw more juice. If they hadn't added that option (I had pre-ordered that first 2400G before they even went on sale) by the time I wanted to deliver it to a customer I would have had to leave a resistor rigged up in there just to burn a couple extra watts of power all the time.
What a change in efficiency compared to traditional setups!!
Simon, I think you'll be pleased with your setup and it will probably pay for itself anyway vs. a used server chip. Excellent for machines anyone wants to leave on all the time, for sure!