A few months ago, I got a nice managed switch for $5, used. It's telnettable and really great. The only problem was that it was "noisy." When I plugged it in, it sounded fine. But after a while, the fan began to whine and it was this horrible "just under the sound of your hearing" whine. It was grating to be in the same room with it. So I looked around online for a new fan, and found one. It arrived today, and I plugged it in. Hmm... not spinning. Then I smelled smoke. Then I SAW smoke! Thick curls of white smoke! I quickly unplugged it. The fan was bad. I'd return it, but it would cost me more to ship it than the fan was worth ($5).
The punchline? The old fan stopped whining.... [wah wah waaaaah]