Here's an example of a power supply without approvals or at least its not marked. This is a "Powmax AG II 480 Watt". I'm sure this one is not marked since I happen to have one. It sells for less than $20 and doesn't have an FCC label or any safety labels either:
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Note that the sale of this power supply is absolutely legal in the U.S.--at least as far as I know. I imagine that the sellers (or re-sellers) could be subject to a law suit, though, if a child was electrocuted or if the supply started a fire if it doesn't have UL. The sale of a power supply without FCC approval does, however, become illegal when a Mom and Pop shop puts it in a computer and sells it.
Here's another example--this one is a 550W. I don't have one of these, but it looks very much like the 480W model that I do have. It's a POWMAX AG II PSAG550A:
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An interesting thing about this power supply is that it is being marketed as having "UL, CB, CE" approvals (but not FCC). However, if you look at the pictures provided in the "Image Viewer", there doesn't appear to be any labels at all on it.
This power supply sells for only $16.99. Here are some example customer reviews:
"I guess I paid for what I got. Had it about 60 days. It seemed to do all right when I installed it. Started smelling and burnt up...."
"You get what you pay for. Burned out in 4 months. Very disappointed. . ."
"This power supply lasted less then 30 days before a coil burnt up. My old 400W was better . . ."
For a picture of a power supply that does have an FCC label on it (and UL/TUV/CB/CUL) look at the Antec SP-400 pictures at:
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Interestingly, this supply also has an "N" mark (Nemko) that isn't documented. According to their website, "NEMKO is a private, independent testing and certification body that can offer technical testing . . . with a view to the protection of human life, the environment and valuable property". This is the sort of power supply that I want in the computer in my home.