> Older computers almost always use more electricity than newer ones
The differences are marginal; my 7 year old i5 really doesn't use that much more power than a modern i5, if it even uses more power in the first place (I don't have a good way to measure this, and with sleep states and whatnot you really need to measure this to be sure).
A few years ago I calculated how much impact it would be if everyone would run a 30W server at their home 24/7; I originally started doing that because someone said that "everyone should just self-host these things at their home", and I wanted to demonstrate that this would have a horrible environmental impact. And turned out my initial thoughts were wrong, and impact was so small that actually, it didn't matter, and I didn't even both posting my comment.
And even if there would be a difference, energy of manufacture tends to outweigh energy usage of usage. There's a long chain of mining, transport, etc. etc. behind all of that I didn't calculate this, but usually the energy differences really do need to be quite substantial to justify the energy usage of manufacture.
Maybe I was horribly wrong and made a mistake; I didn't re-do the calculations for this comment out of laziness. But I do strongly encourage anyone to actually calculate or look up what the impact is, because initial "it's bad for the environment"-feelings could very well be wrong, and no one is served if attention, money, and effort is spent in the wrong places.