Let's say, i use my personal computer for office tasks only and am happy with its performance as long as the operating system and the browser receive regular security updates.
What would be a promising choice of - hardware - operating system - broswer to achieve a long lifetime for the system?
What resources (like ifixit.com) can help with this?
There are some differences began the situation for laptops and desktops, as well as some common solutions. Desktop machines obviously use more resources in manufacturing, and may use more electricity, but are more repairable and upgradable. My case and power supply are 17 years old, though most other components are newer.
Upgrades to keep a machine working longer:
These are both possible on desktops, and some (larger) laptops. Ultra portable laptops can't be upgraded as components are soldered to the motherboard, so they aren't really very repairable either.
Operating system: I've just set up a 12-year-old laptop for school work, web browsing etc. It's running the latest version of a lightweight Linux distribution (Xubuntu 20.04 long term support) and runs faster than a much newer Windows 10 machine. I put an old solid state hard drive in it. OS (and browser) updates will keep going for quite a few years.
Software: The latest Firefox is very quick on that old machine, libre office acceptably so. Firefox is probably the most likely major browser to keep supporting 32-bit systems if you've already got old hardware. Most other office/school tasks like photo editing (GIMP) and vector graphics (Inkscape) work well on low spec hardware. The are many games suitable for casual play.
Open source software support for old hardware is generally better than software from companies that rely on selling you stuff. The only thing that old laptop lacks is DVI output (and my TV doesn't have VGA).
Basically, begin with a computer that has the number of processing cores of current premium computer offerings. Then choose an operating system that is a current offering on premium computers. Basically, begin with a premium-level computer.
Then reduce the number of re-boots for long computer life. And current computers seem to have very good sleep modes and very good stability for fewer necessary re-boots. However, a computer automatically jumping in and out of sleep mode can reduce the life of the computer monitor. So turn the monitor off when allowing the computer to sit in sleep mode.
Also, consider buying the computer from a computer maker and not from a retail store. A retail store can install their own configured version of the operating system on the computer. In that case a complete re-install of the OS from the recovery partition could possibly be a smaller OS install and a better performing OS.
The computer can have more than one operating system which is something to consider but the current method allows changing from one OS to another without a re-boot. That method is to complicated and risky to my thinking. Separate hard-drive partitions for different operating systems might be more stable but requires a re-boot to change between operating systems. But that's two operating systems on one hard-drive. I have previously had two hard-drives with a different operating system on each of the hard-drives. To re-boot to a different hard-drive required switching the wiring plugs inside the computer. Of course removable hard-drives are available. But a computer that is ordered with two internal hard-drives is basically just a system of file back-up and not two different operating systems.
As for a browser my current tip is that the computer might be more stable when the browser is configured to not allow motion detection by websites.
