You will never find one of these units in a name brand PC, ever. This is a PC shop and DIY thing. Most PC shops have become aware of the problem (the one I got for FREE with a case never left my house, I take some pride in what I sell!) I still see them in PCs made by a shop in town that went under a few years ago, and almost always they come back to the customer with a new UL listed, heavy as heck PSU.
I don't think the sample I had from my friend's PC was UL listed I tossed the unit a while ago so I can't check. Of course, that's the first clue that they are junk. The second clue, and one that should give it away immediately is how flimsy the product feels. They weigh about half what a good one would of the same rated output.
As for UL or CSA listings, the product description on newegg.com says they are listed, however on a few units when you look at the label on the unit itself, no such mark can be found. Rumor has it that the importers of these POS units will send one unit to test and import another.
I have complained to newegg.com, but they don't care, the Powmax (the worst of the brands by far) units sell like hotcakes to idiots that measure quality based on how flashy something looks or how good of a "bargain" it is. Newegg is owned by Amazon.com and something tells me they aren't going to consider an email from one person in deciding to suddenly stop carrying a product. Maybe they should look at the reviews, others are not pleased. The ones that are pleased have systems that don't even put a 50% load on these. A PC with one HDD, a DVD drive and a basic Celeron CPU doesn't draw even 200W.
The new ones that are UL listed and DO have a fuse and most of the time, a basic EMI filter (one cap, one choke in hot and neutral), however, they still cannot hold rated load or even close. So they may not burn the house but they are still perfectly capable of taking out a motherboard or CPU. Worst of all, the hard disk usually gets damaged when the things go boom and customers don't usually back up regularly.
As for market forces, they exist on price alone. One of these POS special "550W" units costs about $25, a good 550W unit is around $85-$100. If it's too good to be true, it IS!
Some of the PC shops that used these have gone under due to huge warranty costs and a bad reputation. Now that DIY PC assembly has taken off, these crap PSUs have an even larger market. The average PC DIY with a how to book doesn't know jack about electricity. They don't understand how a PSU with an input rating of 115V @ 2.5A couldn't possibly even come close to putting out 500W. The DIY or uneducated customer is thinking this when I try to explain: conservation of energy? huh? what? Just because they can put a card in a slot doesn't mean they know what they are doing.... kinda like a DIY with a wiring book from Lowes doesn't know how to safely wire his house!
