Earlier quoted context omitted.
I think we need to take a step back and see the big picture. There are 10-year olds computers sitting unused; as a whole, it can fill a percentage of usages. If it does then the people using them don't need to buy another one, new or refurbished. If they don't need to buy, other people can't sell as easily. If they can't sell as easily, they might use it longer, and not need/want to buy another one, old or refurbishe…
I believe many of us are aware of the bigger picture outlined by you, but you keep ignoring the point that the previous 10-year old computers burn much more electricity. And as I already said, the newer more efficient machines have been built already so we might as well use them and help the planet by using less watts. The process you describe is yet to happen e.g. the computers I have I don't want to replace unless…
To first order the upper bound for carbon cost of production/recycling is going to be a multiple of the energy required to melt the components. Call that multiple four: production of raw materials + reshaping in factory + recycling of materials at EOL + energy cost for assembly. So a rough upper limit of the energy to switch a computers would be four times the energy to heat the computer's mass in water (4 J/gC) up to the melting point of silica (1900 C), and a rough lower bound would be the same using the heat capcity and melting point of iron (10x lower heat capacity, 1500 C), and neglecting assembly. For 1 kg of material, that gives a range of 1.8 and 32 MJ. Now you can compare to the energy used. For myself, I'm on a 2 kg laptop that draws up to 250W, but conservatively 50W. That adds up to 32 MJ/kg in 400 h. If I can reduce the energy use by 5W with a new model, that will pay itself back in 2 years of workday computation. Crazy.
Caveat: there will be additional non-CO2 environmental costs. Most components are not recycled, and resource extraction is also environmentally damaging.