The power lead was faulty? Well, Im not a broadband expert - but I can tell you in all the years i've been working in computing (and since BB became popular) i've never seen speed affected by a faulty power cable! Wonder if the covered up another problem with a story?
Who cares! As long as you're surfing at full speed!
(torrent download speeds however, depend on the seed and peer ratio, and also depend on ports being open on your router. If ports are incorrectly opened, you'll see speeds of around 60k. You need to (usually) open up UDP/TCP port 6881 on your router to get torrents to run at full speed.