Currently I have been managing a HP/Dell network consisting of 700 workstations and 3 Servers. In 5 years I've never had a problem with a power supply.
I've only ever had problems with PSU's in custom made PC's.... It's always been because of the PSU not supplying enough power to the system. As long as it's big enough, you should be fine. I mean, are the power supplies that come with Dell, HP, Acer and Toshiba of good quality? I'd say probably not, but with so many enthusiasts among us they will probably tell you Coolermaster is crap.... yet it's still most likely better quality then what comes with pre-built systems.
But I think it was Erasmus who pointed out earlier, if you can find the known "better quality" PSU's at very similar prices... I guess it's up you if you want to be extra safe or not. But I don't think it's much of an issue.
A standard workstation without a dedicated video card? A 200W power supply would almost be over-specced for that, so I can see why the bulk 400W or so things they probably just whack in as standard don't have big problems. They also probably draw little current, so you don't have to worry about rails, etc.
I've personally only ever had one PSU die on me. But you hear things about PSUs that just melt down and destroy entire systems. So when it comes down to comparing say, $40 worth of an unknown unit from an unkown manufacturer from a reseller known for having -some- models that are not so good, or paying $60 for a highly recommended well-built unit and saving yourself the hassle of wondering exactly what you're getting, I think it's silly to have the PSU be the thing you skimp out on (if that $20 can't be trimmed elsewhere or mean you won't eat for a week or something silly).
That's really the point I'm trying to make here... You might get that case/psu combo and it works fine for 20 years, but you really have no idea what you're buying, and I don't like that kind of risk when I can help it.
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