system
A chat on subreddit /r/pcmasterrace
human
I'd like to install Windows 10 on an age old Pentium 4 laptop, just to see what happens. How do I go about it? Do I have to install the LTSC version or something?
gpt
Phoenix Ultra Lite OS

Google it, go on their website, download litest build they offer.

You can use LTSC is you want something straight from Microsoft but you can't download it as Microsoft doesn't offer download so you will be downloading LTSC from some sketchy source which defeates the purpose and LTSC is still not as lite as Phoenix Ultra Lite OS. That thing has stripped basically everything kind of bloat away and left only core windos which makes it run well on old core 2 duos and Pentium 4 PCs

Of and once you are done having fun and actually want to get the most out of that Pentium 4 PC install Windows 7 on it and make it a retro gaming pc from 2000

And if you want Linux PC you will get fastest performance in LXQT Ubuntu aka Lubuntu