That sort of thing usually just goes in the trash here, life is too short.
I mean on a good day you might manage to salvage an impressively cheap power supply (But that will be the only impressive thing about it), or maybe a used hard disk, everything else in a mass market consumer box like that will be on some sort of undocumented SOC. Occasionally a modem will have a usable pulse transformer or something but they are cheap enough I would rather just add them to the next Mouser order then spend the time to rip one out of some old junk.
No, good junk is usually industrial rather then consumer, much more prone to quality parts, and often the parts have actual datasheets.
Regards, Dan.