OK, I've been sufficiently frightened to buy a ridiculously expensive $80
PSU which I got this morning at FRY's. This one:

http://www.antec.com/us/productDetai...?ProdID=26500#



Hope it was worth it.


Analabha

Analabha Roy wrote:

> kony wrote:
>
>> On Wed, 17 Aug 2005 05:46:43 -0500, Analabha Roy
>> <daneelNOSPAM@physics.utexas.edu> wrote:
>>
>>>kony wrote:
>>>
>>>> On Tue, 16 Aug 2005 08:52:47 -0500, Analabha Roy
>>>> <daneelNOSPAM@physics.utexas.edu> wrote:
>>>>
>>>>>
>>>>> Can anybody say anything about that with these specs?
>>>>>
>>>>>http://www.coolmaxusa.com/productDet...ategory=single
>>>>>
>>>>>
>>>>
>>>> That they're peak ratings, not sustainable. Essentially
>>>> they use questinable methods to determine those numbers and
>>>> if other name-brand manufacturers used similar methods,
>>>> their "400W" psu would be rated higher than 400W.
>>>
>>>
>>> That's a good point I guess...
>>>
>>> But what is a psu exactly? Isn't it just a step-down transformer with
>>> some
>>>pots in it to regulate voltage?
>>
>> Not exactly it swithces HV across a transformer at high
>> frequency with a duration or rate controlled by (a
>> controller, to regulate the voltage through at least one or
>> multiple feedbacks) into rectification diodes and (typically
>> inductive and capacitive) filters...
>>
>
>
> Oh, so an AC/DC Converter. Right.
> Thanks for the info. I"ll look it up and dust off my old undergrad
> electricity/electronics textbooks.
>
>> That's an oversimplification and ignores complimentary
>> circuits like the shutdown, fan control, 5VSB, and more,
>> but thinking "it's simple therefore should be cheap" isn't
>> true, as any kind of electronic components have tolerances,
>> values, and more or less elaborate designs including the
>> filtering and lifespan. There are a few PSU schematics
>> scattered over the web, Google may find some. Unfortunately
>> those I've seen are rather simple schematics, more typical
>> of low end PSU that decent ones.
>>
>> I'd return the PSU you bought, but you might pop open some
>> old generic and compare it to a decent PSU. WIthout more
>> experneice in switching PSU you may not realize the
>> significance of all of the differences but even an untrained
>> eye can spot a lot of difference between two "supposedly"
>> 400W PSU, one good and one not.
>>
>>>I mean, it doesn't actually supply any
>>>power, right? That comes from the mains.
>>
>> You might be trying to overthink the definition of supply,
>> and should see it within the context of an electronic
>> device... within that context, it is suitably called a
>> "power supply".
>>
>>
>>>The 'sustainability' would have to
>>>be more dependent on material properties (if the impedance changes too
>>>much as it gets hotter and if subsequent cooling reverses the trend)like
>>>resilience and stuff. If that is true, then the only manufacturing
>>>difference between a high power and low power psu is in the materials
>>>that make the magnetic core, maybe the CPM of the fan, the # of coils in
>>>the transformer and other similar such. Those should be individually
>>>measurable and benchmarkable, and there should be documentation on the
>>>web about ideal parameters and one should be able to compare them.
>>
>> Yes the parameters can be physically compared, though again
>> you're oversimplifing. You have a good point about the core
>> though, the size of the transfomer is indeed "one" of the
>> common differences between a properly rated and a misrated
>> PSU, and/or the construction of the core, whether it be a
>> ferric composite material or old school laminate type. If
>> you dig deep enough you will find that budget grade (junk)
>> PSU cut corners in many, many ways. You will notice more
>> similar build in a generic 400W and a name-brand 250W than a
>> generic 400W and a name-brand 350W.
>>
>>
>>
>>>
>>> Let me know what you think. Also, if you do know of some urls where they
>>>have additional info, I'd be interested in reading it.
>>
>>
>> I would first suggest some background reading, either on
>> switching power supplies in general or if necessary, even
>> more basic like electronics in general. It's not the kind
>> of think I can condense into a few usenet posts and I don't
>> know of any website that does so either, as you first need
>> the requisite background on power, electronics, SMPS,
>> computer power demands, then to tie it all together in
>> context plus survey enough power supplies (including failure
>> modes of dead ones) to get a better picture.