It had an i3 which I bumped up to an i5-750 (it only cost 4 euros) but it's socket 1156 era, so probably still rather inefficient compared to recent gens, right?

I’ll hit you up elsewhere a bit later and share some ideas for backup :)

thanks! that would be great. I already have a NAS with redundancy for my important stuff, but I'm starting to build a large archive of downloaded youtube videos for research projects and I would hate to lose them.