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lastly I have been getting used laptops for the last few years which I think are the best choice.
In principle, this is actually a very good and, above all, cost-effective idea. But aren't the devices significantly higher in terms of power consumption than a Raspberry, for example? At least if the laptop has a dedicated graphics card, that's a few watts that the laptop needs ...
For us, the energy costs actually play a role in the profitability calculation ...