Originally posted by: tcsenter
I've never heard that before. In fact, FSP PSUs are generally regarded to be under-specified, meaning, that they will run stably beyond the specs listed on their label. Now how could they do that, if they were somehow output-limited? I've never heard of such a thing.
FSP PSUs are conservatively rated - all of them - by the same method FSP uses to rate its power supplies. e.g. if a 250W model is 15% under-rated, so is the 300W.
And of course power supplies are output limited, where do you think "Total Power" comes from? Have you never seen product specs state "total power shall not exceed..." or "+3.3V and +5V combined shall not exceed..."? What on earth did you think that meant?
It appears we need a little remedial course on how to read a PSU label:
And someone needs a remedial course on comprehension and logic, tempered by a technical understanding of how a power-supply works, is designed, and the operating requirements of such that would prohibit your theory from being true.
There's a difference between an engine being rated for so many RPMs before "going into the redline zone", and at what engine operating temperatures, and an engine that is designed with an intentional RPM-governor, that will kill the ignition/spark entirely if it hits that RPM range.
PSUs, due to the fact that they need to supply higher levels of inrush current during the power-on phase of your computer, do not have any sort of governor, or output-power limiter. What they do have, on good-quality ones, are safety-related features, such as overcurrent or overtemperature protection. (Like a car engine that would safely cut itself off, if the engine was overheating and in danger of seizing, but not simply because it had reached a certain output RPM number.)
Those "shall not exceed" ratings, are in terms of safe, continous operation, below the "redline" of the PSU. If you read some PSU labels, they
also specify a "max peak" load, which is
higher than those "shall not exceed" ratings - but limited in duration to a very short period of time, sometimes also specified, sometimes not.
In short, every single consumer-level PC PSU that I've ever seen, didn't have any sort of "RPM governor" on it. Safety features yes, "limiter", no.
Originally posted by: tcsenter
FSP/Sparkle does not characterize the output of their power supplies any different than other manufacturers of quality power supplies.
...
I have said numerous times before that Fortron/Sparkle make quality power supplies that are conservatively rated, but there ain't no 250W FSP model that offers output even approaching any good 350W models, whether by Antec, Enermax, or other brand.
What part of 350W > 250W don't you understand?
What part of el-cheapo power-supply ratings-games, don't you understand?
You do realize, that those numbers aren't in any way an absolute, right? (As your theory of "output limited" power-supply design would apparently require.) That those numbers, are derived from a "derating curve", that involves combinations of loads, at varying temperature ranges? (Another reason why the specs that you stated, are missing lots of information - there is no statement on the temp ranges that those documented supported loads apply to.)
The fact is, that compared to most of their competitors (some other high-quality PSU mfgs excluded), they
do characterize their PSUs differently, if only because they tend to use more realistic test parameters, such as temp, while doing their PSU testing/characterization. If you look at the ratings of most cheapo PSUs, they were tested at their listed ratings, at a very
unrealistic temperature rating, often 25C. If you look at the detailed specs on most FSP PSUs, they list the temp for the listed ratings, at something far more robust, as high as 40C or so. (I'd have to double-check to confirm the actual value, I don't recall right now.) But those numbers are definately different, and they are vitally important in "translating" the other listed power-output values, into something more comparable. IOW, attempting to compare the listed output power between an FSP PSU, and a non-FSP PSU, absent the information about the temps, is literally comparing apples to oranges. (Some PSU mfgs, actually print a graph, either on the label, or in the manual, showing the different output power ratings, at different temperatures. They basically show you the entire de-rating curve. PC Power & Cooling's web site has a good explaination of this too, IIRC.)
However, that little rant was mostly aimed at the idea of comparing FSP to non-FSP PSUs. Comparing FSP to FSP.. well, that
is a bit more of an apples-to-apples comparison. Assuming that there isn't otherwise any difference in terms of quality or ratings, then a higher-rated FSP PSU should be better than a lower-rated FSP PSU. But in comparison to a non-FSP PSU, a 250W PSU is
still generally better than a good portion of the up-to-"450W"-rated generic PSUs on the market, and *that's* what makes this thread a "Hot Deal".
Originally posted by: tcsenter
Did you miss the part about how Fortron, like any other mfg, has different lines, with different features and cost/performance tradeoffs? It's likely that the -GU is their lower-cost line, as far as I can tell. That doesn't make it bad, but not every Fortron is built the same either.
FSP model naming convention has nothing to do with the quality. It has to do with features and air flow through the chassis. e.g. GT model has air flow IN from the top and OUT through the rear; GN and BN model has air flow IN from the front and OUT through the rear; GI model has air flow IN from the rear and OUT through the top (or bottom, depending on your orientation). I don't know what all the model designations mean, but I do know they designate chassis air flow design and PSU features, they do not designate quality grade or output differences. FSP provides datasheets for all its models, perhaps you would benefit from a rendevous with Adobe Reader and FSP datasheets.
Questions?
Thanks for that info, I guess I should familiarize myself a bit more with the model numbers and not be lazy, eh? I would be very surprised to find out that there was no price/performance or price/quality tradeoffs within FSP's entire product model line though. Every mfg does, although I'm sure that the minimum quality level of FSP's even lowest-end PSUs is still quite good.
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