Name brand vs Generic......

[FPS]

I recently got into an argument with my dad about Power supplies's,
He seems to think that generic psu's are no differant to say an Antec or the new OCZ's. (not the 600w ones)

What I wann know is, what can a name brand PSU do better than a generic psu?

 

[_Korruption_]

What I wann know is, what can a name brand PSU do better than a generic psu?

Reduce the overall weight of your computer system by using cheaper components inside the PSU? Quality PSUs should add quite a bit of weight to your case. The generic cheapies aren't even cheap, when you have to spend money replacing them several times. Its just not worth the trouble.

 

[Ice Czar]

your dad is stuck in a time warp
drag him on in here and we'll school him

in short most generics cant be trusted
of course many brandname supplies cant be either
PSUs are alot more complicated than just a few years ago
refer to the FAQs
HOW TO BUY A PSU
and Watts dont mean Jack

POWER SHMOWER by Mike Chin

or How PSU Power Ratings Mean Almost Nothing

A frustrating fact about PSUs is that there does not appear to be a stringent or regulated standard for reporting, advertising and labeling rated power. This is despite the existence of standards like ATX2.03 or Intel ATX12V.

There are well-established standards for measuring and rating HDD capacity, an engine's horsepower, or the heat generated by a furnace... but not one for how much power a PSU can deliver. There are so many cases of people with "450W" PSUs having power stability issues running a system that can't possoibly draw more than 150W. And "300W" units that keep running where the "450W" units are faltering.

It's not just about bad PSUs vs better ones. It's a dumb situation caused by uncontrolled marketing competition. Real regulation would bring PSUs out of snake oil territory and into a more sensible consumer-friendly terrain.

There are many ways PSU makers fudge to make their units seem more powerful.

1) Out and out lying. You add up the power on all the lines in many PSUs and they fall short of the rated power by 10, 20 30W or even more.

There are more sophisticated ways:

2) Limit the AC input voltage to a very narrow tolerance. The best PSUs are able to deliver their rated power given a decent range of AC input power, say 90~130V for a 120V unit. It's much more demanding to produce 300W w/90VAC input than with 120VAC, so what some PSU makers will detail in their tech specs (usually not in their consumer brochures) is to specify 115-120VAC for input power. A PSU specified this way will not deliver full power if the AC voltage sags, if there is a brown-out. Surely it causes instability more often than a PSU rated to deliver full power with 90-130VAC.

3) Specify a low operating temperature for rated output. This is quite common, but again not often seen in consumer brochures, but rather tech spec sheets provided usually only on demand by engineers or corp buyers. A typical PSU operating temp statement is somthing like this:

0ºC ~25ºC for full rating of load, decrease to zero Watts O/P at 70ºC

Examine what that says. Full power (let's say 400W) is available when the unit is at 0ºC ~25ºC. Hmmm. Think about this.

Have you ever felt air blown out of a PSU in a PC running absolutely full tilt (which it would have to do to get anywhere near 400W output) that felt cool to the fingers? 25ºC airflow would feel exactly that: Cool, given that normal body temperature is 37 °C.

So this PSU cannot deliver full rated power when its temperature goes over 25ºC. OK, what happens to the max power output capacity above that temp? It decreases gradually so that by the time the PSU temp reaches 70ºC, the PSU cannot deliver any power at all. So if you assume that this power drop as temp rises is linear, then max power capacity will drop by ~9W for every degree over 25ºC.

Now having examined as many PSUs as I have over the last 2~3 years, I have to say there's not a single PSU in ANY PC I have ever used or examined that would not measure at least 30~35ºC almost anywhere inside the PSU under almost any kind of load. And if/when it is pushed, 45ºC is nothing at all, especially for or near hot running components like voltage regulators.

So let's say 40ºC is a fairly typical temp inside a PSU. This 400W rated unit would actually be able to deliver a max of just 220W at that temp. Hmmm. Interesting, isn't it? At 50ºC, the available power would drop to just 130W. No wonder some PSUs have 3 fans each capable of 50 cfm!!

Here's a simple fact: Really high quality PSUs are actually rated for full power output at as high as 40ºC. The trick is get a hold of the spec sheets that tell such information so you can compare apples to apples. Or ask.

or

from dansdata

Unethical PSU Marketing 101.

Here's how to make overly optimistic power supply specifications. It's really simple.

First, power the thing up. You can make an ATX power supply that isn't connected to a motherboard turn on by grounding pin number 14 on the big motherboard power connector. It's easy to spot that pin, because it's the only one with a green wire going to it.

Use any handy bit of wire - like the paper clip in this picture - to connect pin 14 to any ground contact. The ground contacts are the ones with the black wires going to them. Presto, the PSU will turn on.

Now, break out your brick-sized power resistors and load the heck out of one of the output rails - the +5V rail, for instance. Measure the current as you increase the load, until the voltage sags unacceptably far below the rated voltage.

How do you tell what an unacceptable voltage sag is? Well, you could choose a nice conservative small permitted sag - say, 0.1 volts - so that your results are genuinely useful to your customers. Or you could just ignore the voltage and say that when a fuse (or some other component...) blows, that must have been the limit, right there.

OK. Now you've made a big fat amperage number for the +5V rail. If you blew up the PSU in the process, get another one, and repeat the process for +12V and +3.3V, and for the low current rails as well.

On no account, though, should you test more than one rail at a time. This is the key to the whole scam.

A big beefy PSU may be able to deliver 50 amps (say) on the 5V rail when nothing else is under load, and 25 amps (say) on the 12V rail when it's similarly all alone. But the 12V and 5V rails together may only be able to deliver, say, 350 watts between them, when they're both under load. Watts equals amps times volts.

In a real PC, all of the power rails will always be under load together.

But you're not testing what the PSU can really do - you're making pretty numbers for the sales brochure!

So test all of your rails alone, get an amperage figure for all of them, multiply that figure by the voltage of the rail it came from (the nominal voltage, not whatever the voltage had sagged to as the PSU pumped electrons through the dessert spoon you'd soldered to the circuit board), then take all of the resulting wattage figures and add 'em up. That's a wrap, folks. Ship it!

Power supplies become increasingly expensive

When I initially asked about this on a mailing list, Solaris x86 advocate Al Hopper told me I was drowning in my tea, and that it was "all very simple". I love the simplicity of Unix people.

He explained that the later P4 CPUs take their power from a 12 Volt feed and, using the onboard voltage regulators, generate the high current, low-voltages they need to operate (anywhere from ~ 1.6V to around 2.7V). So the first requirement is a PSU that has plenty of power available from the 12V supply. Since the older ATX compatible PSUs didn't supply much current from the 12V section you have to ensure that your new PS delivers enough current (or power in Watts) from the 12V section. That's why using your old P3 ATX PS is a big "no-no".

He then described the history of the post-P3 power supply mess:

The earlier Athlon motherboard manufacturers decided to solve the 12v problem by using an additional 4-pin square connector to get the extra 12V those CPUs required. However many older PSUs didn't provide the 12V 4-pin square connector.

The motherboard makers then wised up and decided that there was nothing magical about a square 4-pin connector, so they put a normal hard disk type socket on the motherboard and provided the 12v power via a standard hard disk (4-pin inline) connector. Problem solved - you may now use your older PSUs provided they supply sufficient 12V current (many did not).

Further confusion came from PSU manufacturers not specifying the capabilities of the PSU in a way that allowed the end user to verify it's 12V power output rating.

In the meantime the ATX spec was saying "use the new 6-pin" inline connector - and very few motherboard makers implemented it.

Just to be sure, some motherboard makers, implemented *both* the hard disk style 4-pin inline connector and the square 4-pin connector. They said "use either or both in any combination you like".

The spec then evolved to the 24-pin main connector. Again, most motherboard manufacturers did not wish to make their customers mad by mandating that they replace their power supplies. This might cause their customers to avoid motherboard upgrades. Some used a "special" 24-pin connector with the extra 4-pin connection blocked off, or colored so that the user could plugin a 20-pin plug into the correct end of the 24-pin socket on the motherboard. Many others simply ignored the 24-pin requirement in the specs. Again - problem solved - use your older PSU.

Power Supplies are all about the worse case senerio
too high a draw, too high a temperature, too unstable a source AC Power
and supplys that under normal circumstances are adequate, blowup and often kill stuff
(this can happen to even quality supplies, but they should shutdown safely withoput killing components)
so we are a pretty conservative lot in here, considering the power supply has the potential to fry components worth exponentially more that it is.

To make matters worse there are very very few reviewers able to review a supply, the best that can be said for most of them is that it didnt blow up their config that day, because the power from their outlet happend to be stable that day, they didnt overload it and it wasnt too hot.

exceptions are rare
http://www.leesspace.com/Published_reviews.htm
http://www.silentpcreview.com/section4.html

so get as good a UPS, Thermal Solution, and PSU that will actually power your connfig with room to spare as you can afford

part of the bad rap generics get is do to the public buying the line of bullshit they feed them and overloading them
the rest is from value engineered components, PSU at that level are a commodity
which never bodes well for quality

 

[BossNoodleKaboodle]

Generic things of any kind, PSU's included, are designed for the uninformed masses who don't really know or care how things work, and are happy to replace them when they inexplicably fail. You dad needs a lesson in COST VS VALUE. Like the other guy said, You'll end up spending as much, if not more, on crappy PSU's AND system components it takes with it when they die, than buying a good one in the first place. Doesn't he realize that the generic ones are the cheapest components, slapped together, falsely advertized and then sold to unsuspecting and uninformed people? He surely doesn't want to be one of those people getting RIPPED OFF since hes so concerned with saving money and good value...

 

[FPS]

thanks everyone
this is what i wanted, ill show this to my dad when he gets home

 

[seanmcd]

Tell your dad to search this or any forum on power supply's long enough and he will eventually look at you and say, "Ok, I was wrong"

Partly, he is right. There are quite a few "generic" brands that work great. But these days there are WAY too many ultra cheap "generic" psu's that either don't last longer than three months or can't power today's "custom/power user" computers. I've experienced it first hand. I've listened to countless friends talk about how crappy their computer runs (either freezing, rebooting, locking up, etc.) and it turned out to be the Generic PSU (and case) they got off of ebay for $29. And finally, I've read it here in the forums time and time again.

 

[darktiger]

I would not let your dad post on this forum...There are mean people around which will try to flame him if he says Generic PSU is no different than Namebrand/Reliable PSU...

 

[Ice Czar]

There are mean people around

they are however relatively easy to recognize