> Replacing really obsolete machines used as servers by RPI does certainly makes sense power-wise (as long as you don't need storage)
You do need storage, but you need it for all of them anyways. I certainly won't trust the original spinning disk HDD that comes with hand me down machines with anything more than an OS image. Everything else goes on the NAS.
> However, I agree with with the OP comment that computer should not be replaced simply because newer, more energy efficient alternatives exist: at least not for anything made after 2010.
This - this is where the answer is to measure it. Sometimes the result will surprise you quite a bit. Most machines made after 2010 will be fine, but trust me, it's really worth plugging it into a watt meter and making sure.
Turns out all sorts of things adjust power draw, and one of the least maintained parts of old machines is the PSU - usually it's filled with dust/dirt, and as long as the machine still runs no one has paid it any mind in the last 10 years.
> Not saying I would not still buy a M1 over keeping the slow Mac Intel but please don't claim your are helping the environment when doing so
Who the fuck is talking about replacing an intel macbook with an m1? I'm talking about getting old tower machines from office/school closeouts or as hand-me-downs and repurposing them. An intel mac (even a 2010-2013 era one) is still worth WAY more than an RPI (~$200 vs $40), and laptops in general use a very different power curve (batteries matter - who knew...?).
Not to mention you can't even run a decent OS on the modern intel macs after 2016... (although at least Asahi is making progress these days) so trust me - I'm hardly suggesting a macbook update (I would strongly suggest purchasing from a different company, though - but that's a different conversation related to a different set of morals).