What a root!
They’re long, very long. And they don’t go down. Cactus roots extend horizontally hundreds of meters. Why? Because they create a stable base to keep them straight. And one more information about irrigation: if you wet them continuously, these ends rot.
Computers and cactus, urban legend?
They have not proved very effective in absorbing electromagnetic waves because, in addition, to serve something should be between the computer and you, not next, which would make them unpracticable. Yes, decorating the desk are beautiful.