Seriously. 24/7 adds up faster than most realize!

The idle wattage per module has shrunk from 2.5-3W down to 1-1.2 between DDR3 & DDR5. Assuming a 1.3W difference (so 10.4W for 8760 hours), a DDR3 machine with 8 sticks would increase your yearly power consumption by almost 1% (assuming avg 10,500kWh/yr household)

That's only a couple dollars in most cases but the gap is only larger in every other instance. When I upgraded from Zen 2 to Zen 3 it was able to complete the same workload just as fast with half as many cores while pulling over 100W less. Sustained 100% utilization barely even heats a room effectively anymore!

Wake on LAN?

Then you cannot enjoy some very useful and used home server functions like home automation or NVR.

The one thing to be careful with Zen 2 onwards is that if your server is going to be idling most of the time then the majority of your power usage comes from the IO die. Quite a few times you'd be better off with the "less efficient" Intel chips because they save 10-20 Watts when doing nothing.

A similar one I just ran into: my Framework Desktop was idling @ 5W more than other reported numbers. Issue turned out to be the 10 year old ATX PSU I was using.

Maybe? The price difference on newer hardware can buy a lot of electricity, and if you aren't running stuff at 100% all the time the calculation changes again. Idle power draw on a brand new server isn't significantly different from one that's 5 years old.

To be clear, this server is very lightly loaded, it's just running our internal network services (file server, VPN/DNS, various web apps, SVN etc.) so it's not like we're flogging a room full of GeForce 1080Ti cards instead of buying a new 4090Ti or whatever. Also it's at work so it doesn't impact the home power bill. :D