mentioned go out for bids for their parts and buy from the low bidder. In short there are a lot of crappy power supplies out there that can't really supply their rated wattage for very long. The real crap stuff seemed to start showing up in the 300 Watt Power Supplies, when demand and competiton was high.
If you simply scan these forums a huge portion of the threads include "replace the power supply" when having flaky performance..
The four year one is nothing to worry about. To do a thorough analysis would require detailed knowledge of what is in each computer and what power supply ratings, max and nominal are.
If you have one particular sysem that has blown a number of power supplies, Robert Proffitt has posted the experience that his shop has had re such. Basically it is the fact that the mobo's have defective capacitors on them. There was a major incident about three years ago where a huge batch of defective capacitors got into systems. Robert can give a link to the article on the subject.
And, of course, some of those capacitors get put into power supplies and fail there.
Our little early stage company has seen the demise of 8 desktop PC power supplies (of 15 desktops) in the last two years, since we moved into a new building. There is no clear correlation that would ID the failures. Age at death ranged from 60 days to over four years. Location doesn't seem to matter as we have had PC's croak in a materials laboratory, an administrative office, and a shipping/receiving area. We suspected the carbon fibers we sometimes work with could be shorting the supplies, so we ran a one week sample test with a HEPA filter placed right in the heart of where we were working with carbon fabric. Characterization of the filtered material found no organic fibers and lots of particles consistent in size and shape with household dusts. All but one of the PC's were running off of garden variety UPS backups when they were stricken. In one case a replacement power supply expired on restart. In another, the replacement PS worked, but was unable to revive the motherboard.
Whatever is causing it has as much brand loyalty as we do. The obits include 2 Compaqs, 2 Dells, 1 eMachines, 1 Gateway. 1 IBM, and 1 Northgate. None of our seven notebook computers have been affected.
Personal computers used for PC stuff appear to be most vulnerable. The same labs where some of the PC's failed also house PC equipped analytical instruments and none of them had the problem.
Monitoring of the power supply in our 35 year old building says our power quality is pretty darn good. So my questions are: 1) Has anybody ever seen anything like this before?; 2) If yes, can you tell us what it is?; 3) If no, do you have any suggestions on where to look?
Any ideas would be much appreciated.

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