Modern hardware has backdoors that can't be disabled.

So does older hardware, nothing was gained here.

Is there any proof that such potential backdoors are practical and not theoretical? Have you considered non x86 hardware. If you were made of money for example Talos II or other more reasonable priced options?

Why? They all still accomplish what I need them to.

For a given task, newer computers are more efficient than old computers. My 20 watt Intel NUC easily fills a role that I used to fill with a 200 watt surplus PC.

Whether or not an upgrade for efficiency is worth it is subjective though.

Modern hardware isn't much faster.

2023 hardware is much faster than 2014 hardware.

So much so that 2023 laptops often trounce 2014 desktops, with a fraction of the power budget and cooling capacity.

It was true that power stagnated for a long time but it's finally back on the upturn.