PSU Basic Knowledge

AntecRep

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Dec 22, 2008
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Hello Everyone,

Antec would like to announce that we will try to increase our customer service by becoming a forum member.

With that said, we would like to provide you with information on PSU Basic Knowledge. Thanks for your support.


Q:What is Universal Input?


A:Universal Input means that the power supply (PSU) can be used in any country around the world, with any input voltage from 90~240VAC, without adjusting an input power selector switch.

Q:What is Active PFC and what are the benefits?

A:Without Power Factor Correction (PFC), the normal power factor for a PSU is less than 0.6, which makes it more difficult for the power plant to distribute electricity. Passive PFC can boost the power factor to around 0.7, but that is not a significant improvement. Active PFC can achieve 0.99 and increase the efficiency of the power plant 40%. This is very important in an environmental friendly era.

Q:What is the purpose of electromagnetic interference (EMI) filtering in a power supply?

A:An EMI filter is a required circuit for a PSU. The better the PSU, the better its EMI filter will be designed. The filter?s first job is to prevent the PSU noise from interfering with other electronic devices. Second, it prevents electromagnetic noise from the power grid and other devices from getting into the PSU. When using a bad PSU, there can be ?snow? on the monitor and any nearby TV, or there may be static on the radio.

Q:What are Double Forward Converter circuits and their benefits?

A: Double Forward is the current mainstream of PSU design. It is has many advantages such as high efficiency, low failure rate and high Wattage. The design that it replaced is called Half-bridge. The old design had the advantage of low cost, but the wattage and efficiency could not be improved. Only low end systems are still using Half-bridge design.

  • When the circuit is off, each transistor is subject to half the load present in older designs.
    When the circuit is goes into its off-state, leakage inductance spikes are clamped.

Q:What are the benefits of Double Layer circuit board design?

A: Double Layer has several benefits. The only drawback is higher cost.
  1. An increase in copper foil area decreases loss in current flow.
    Makes printed circuit board (PCB) layout easier and components can be arranged better.
    Fewer jumpers, faster component insertion and easier board assembly.
    Prevents solder cracking when using heavy components.
    Better EMI performance.

Q:For an induction coil, what is the effect of the cross-sectional area of the copper cable?

A:Coils are measured by inductance. For two coils with the same inductance, it is better to use thicker wire. And with the same wattage, it is better with larger adaptor, larger induction coil or larger copper wire.

Q:Is the capacitor an important factor to the life circle of PSU?

A:Capacitors are probably the single most critical component. Using high capacity, high voltage ratings, and low ESR capacitors can greatly improve the PSU life circle. Selecting components with high heat ratings will also enhance the longevity of the unit. Some of the best quality components are of Japanese manufacture.

Q: Does the temperature inside the PSU affect the output efficiency and life circle?

A:Temperature greatly affects the life circle of many components, such as capacitors, resistors, fans, etc. If the temperature increases 10°C, the PSU?s lifetime will decrease by half. For example, if an output capacitor normally has a 3000 hours lifetime at 105°C; then at 95°C it can work 6000 hrs; and 96000 hours at 55°C. For efficiency, it is a different situation. Some components have higher efficiency at low temperature and some perform better when hot. For example, metallic oxide semiconductor field effect transistors (MOSFET) have higher efficiency at lower temperatures.


Q:What are the differences between DC to DC circuit and general Magnetic Amplifier Circuit?

A: DC to DC is going to be the main stream for future high-end PSU, and has the following benefits:
  1. Since all of the 12 volt rails and other independent voltages ultimately start from a single 12V power supply, the min. load of 12V, 5V and 3.3V can be very small or zero. Because there is no min. load, it will not cause compatibility issues in different systems. Since 5V and 3.3V are transferred from 12V, there are always indirect load to 12V from one of each.
    Antec has many power supplies designed with a main 12V core that gets broken out for separate rails. Since all power in our DC to DC design flows from the primary 12V core, all of the voltage rails can share from the same input pool of current for an optimal distribution of power at all times and across all voltages.
    The DC to DC module uses low voltage MOSFET transistors which have low on-state loss. When transforming 12v to 5v or 3.3v, Magnetic Amplifier Circuits have 70 ? 80% efficiency, but DC to DC can reach 90% or higher. It is more environmental friendly.


Q:How is a pulse-width modulation (PWM) fan quieter than a regular fan?

A: PWM fans can run from 15% to 100% of their maximum speed. However, a traditional voltage control fan can only run from 35% to 90% of its maximum speed. Using a PWM fan and running the PSU at 50% load or less, the PSU will be much quieter. Any power supply running at high load will need to run its fan at high speed and will be audible.

Q:What is synchronous rectification and what is its effect on the overall efficiency of the PSU?

A:Synchronous rectification uses low voltage MOSFETs instead of a general rectifier, so its on-state resistance is lower. Synchronous rectification has lower loss so less heat is generated and efficiency is improved.

Q:What is the effect of using DC to DC on the output voltages?

A:The working frequency of a DC to DC voltage regulator module (VRM) is much higher than a Magnetic Amplifier Circuit. That means a DC to DC circuit can provide transient response times as low as 10 microseconds on rails controlled by the VRM. That?s a hundred times faster than standard power supply response times of 1 millisecond (1000 microseconds). This makes the output voltage more stable on the 5v and 3.3v rails, even if the load changes rapidly, and helps protect sensitive components.

Q:Are multiple +12V outputs PSU more stable and reliable than single +12V output PSU?


A:Multiple +12V outputs are mainly used for safety protection. Each output keeps the current within a safe range. Single +12V output is an old design; it is used to avoid wrong activating of protection circuit by mass power consuming from video card. However, it is very dangerous, because when short happens in any component; there will be no over-current protection. It is easy to cause fire, so Antec?s PSUs use multiple +12V outputs to avoid this danger. Some companies try to perpetuate a myth that power can be ?trapped? on a rail. That?s just wrong. Each rail has its own circuitry for the protection of the PSU and the devices connected to it, but there?s no way one rail can limit the total power available on the others.

Q:In regards to the size of DC output cable, is bigger always better?

A:Basically, yes. However, there is still a cost/performance value which should be met and there are also electrical limitations of other components in your computer. Where larger amounts of current are required by components such as graphics cards, multiple wires tend to be used instead of one huge wire. One of the reasons for that has to do with how much current can flow into a motherboard or other printed circuit board at a single point. You gain more contact surface area for lower resistance and more connectors increase reliability of the connection due to redundancy.

Q:What is the 80 PLUS® standard?


A:From the 80 PLUS website, the 80 PLUS program is a unique forum that unites electric utilities, the computer industry and consumers in an effort to bring energy efficient technology solutions to the marketplace.
The 80 PLUS standard has four classes: Standard/Bronze/Silver/Gold. Below is the information table. The basic principle is the efficiency must be at least 80% when the PSU is running at 20% load or higher.

Fraction of Rated Load 20% 50% 100%
80 PLUS 80% 80% 80%
80 PLUS Bronze 82% 85% 82%
80 PLUS Silver 85% 88% 85%
80 PLUS Gold 87% 90% 87%

Q:Is dual PCB better than single PCB?

A:Yes. Dual PCB designs have more flexibility to arrange components and create an efficient air flow. Compared to single PCB, it will have better cooling efficiency.

Q:How do I pick a good PSU?

A:It is not easy for a general user to judge if a PSU is good or not. Here are some principles.
  1. Choose a well-known brand.
    Has the PSU passed safety certifications?
    Is the wattage number the value for peak output or continuous output? Continuous is better.
    Compare the weight with other similar products to see if it is too light.
    (Not suitable for passive PFC power supply)
    Compare the internal components, if they have size difference.
    Does the PSU have the 80 PLUS certification.

Q:What is the meaning and differences of working temperature of a PSU?

A:Generally the working temperature of PSUs in the market is around 25? (environmental temperature). However, inside a case, because of CPU and video card, the temperature is usually higher than 25? (environmental temperature).

Q:Why is Antec?s Signature PSU more expensive than other companies? products?

A:Antec started to design this series based on server standards, and then went beyond. All the components are the best choices and we also added many new designs seen here for the first time in a consumer power supply. The highest quality components. Insane levels of craftsmanship. Brilliant design. Cutting edge features. Put all of that together and you have the power supply equivalent of a high-end race car. Car companies build race cars in order to push automotive technology to new heights. Tough reviewers have noted that the Signature excels in absolutely every aspect of performance, and several reviewers have said that they have never seen a better PSU, ever. It?s also built to last; at 50? and running 24 hrs. at full load, we guarantee it for five years. Based on performance, this is not an expensive PSU. Think of it as a race car that you can afford!

Q:Why are there so many models of PSU with the 80 PLUS label when there aren?t anywhere near that many power supplies listed on the 80 PLUS website?

A:To avoid fake certification, please check with the 80 PLUS official website to see if the products are on the certificate lists or not.

1.Some companies will also change the hardware design to pass the certification, and then the products they send to market don?t meet the standard. Here are some of the tricks:

  1. Cable length of test unit is shorter than the real product.
    Thicker wires are used for testing. After passing the test, the design is changed.
    Better electronic components are installed in the units sent for testing (or units are tested and hand-picked).
    Use better fans and heatsinks or adjust the fan voltage in the cooling system.
    Change EMI design or add jumper under it.

2.It is really difficult for users to determine the internal design. The best way to choose is to select a well-known brand, do comparisons and read reviews.
 

Zap

Elite Member
Oct 13, 1999
22,377
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Originally posted by: AntecRep
Hello Everyone,

Hello AntecRep. Welcome to the forums, and join the other company reps. :beer:

Originally posted by: AntecRep
Some of the best quality components are of Japanese manufacture.

Translation: Antec stopped using Fujiyuu capacitors years ago. ;)

Originally posted by: AntecRep
Some companies try to perpetuate a myth that power can be ?trapped? on a rail. That?s just wrong. Each rail has its own circuitry for the protection of the PSU and the devices connected to it, but there?s no way one rail can limit the total power available on the others.

It's pick on PCP&C day!

Originally posted by: AntecRep
Compare the weight with other similar products to see if it is too light.

Hey, that's what I always said.
 

LOUISSSSS

Diamond Member
Dec 5, 2005
8,771
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what kind of psu would u recommend for the system in my signature? assuming my 610watt psu died...
budget is not a problem and sound if not a problem. modular is optional also
 

AmberClad

Diamond Member
Jul 23, 2005
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Originally posted by: AntecRep
Hello Everyone,

Antec would like to announce that we will try to increase our customer service by becoming a forum member.
There was a member called AntecCSR who used to post here, but it's nice to have someone with a more technical background around, so welcome.



Originally posted by: LOUISSSSS
what kind of psu would u recommend for the system in my signature? assuming my 610watt psu died...
budget is not a problem and sound if not a problem. modular is optional also
If you're really serious about that, then there's the Antec Signature series. If you mean, "within reason", then the Antec Quattro.
 

HOOfan 1

Platinum Member
Sep 2, 2007
2,337
15
81
Originally posted by: AmberClad

Originally posted by: LOUISSSSS
what kind of psu would u recommend for the system in my signature? assuming my 610watt psu died...
budget is not a problem and sound if not a problem. modular is optional also
If you're really serious about that, then there's the Antec Signature series. If you mean, "within reason", then the Antec Quattro.

LOUISSSSS never specified that it had to be an Antec :evil:
 

AmberClad

Diamond Member
Jul 23, 2005
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Originally posted by: HOOfan 1
LOUISSSSS never specified that it had to be an Antec :evil:
I didn't want to be mean and threadcrap AntecRep's thread :p.

Can we let AntecRep and Yellowbeard duke it out in a deathmatch and take bets on the winner :evil:? Maybe have a three way cage match if any of the OCZ reps are still around.
 

AntecRep

Banned
Dec 22, 2008
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Originally posted by: LOUISSSSS
what kind of psu would u recommend for the system in my signature? assuming my 610watt psu died...
budget is not a problem and sound if not a problem. modular is optional also

I might recommend the EA-650 for this system. However, if you want to go to more high end, SG series will be the best choice. You could also visit the Antec PSU Calculator for a more comprehensive list.
 

jonnyGURU

Moderator <BR> Power Supplies
Moderator
Oct 30, 1999
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Good FAQ, but the branding in the post prevents me from stickying it. If you'd like to post an FAQ without the Antec specific items in it, I would gladly stick it.

Thanks!
 

tcsenter

Lifer
Sep 7, 2001
18,356
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Originally posted by: AntecRep
Some companies try to perpetuate a myth that power can be ?trapped? on a rail. That?s just wrong. Each rail has its own circuitry for the protection of the PSU and the devices connected to it, but there?s no way one rail can limit the total power available on the others.
Sure there is. Consider a PSU with these loading limits:

+12V1 @ 17A
+12V2 @ 18A

+12V1 & +12V2 combined = 360W MAX (30A)

Now suppose loading on +12V1 is 19A, shutting the PSU down, while +12V2 was only carrying 6A.

Q. How much of the 30A you paid for do you get from a PSU that has shut down?


Of course, the real problem is that it is entirely possible to create such a disparate loading situation in the first place because the user has no way of knowing which connectors are loading which +12V output. This problem was partially addressed by EPS/SSI that requires some power connectors to be sourced from particular +12V outputs. But there is still real potential for blind loading assumptions to happen because no PSU manufacturer has taken initiative to plainly disclose how ALL power leads are distributed between the +12V outputs. Will Antec be a leader on this or just another cow in the herd?

Furthermore, a PSU company ought to know better than anyone that total DC output is informationally worthless way to recommend or estimate PSU requirements. Yet, we continue to see "power supply calculators" that must overestimate total DC output because it is a grossly imprecise method. We all know the correct and proper way is to calculate LOADING. Knowing the amps tell us everything we need to know about wattage, but knowing only total wattage is worthless.

Intel and AMD release the electrical loading figures for CPUs, as do all the hard drive, optical drive, and DC fan manufacturers (or its specified on the label). The major information black-out is for graphics cards. When I have contacted NVIDIA and ATI to request loading data for their reference cards instead of worthless PSU DC output minimums, they respond "We'll get right on that, Buddy" and nothing ever happens. I seriously doubt an industry leading company like Antec would have no more success at prying this information from NVIDIA and ATI/AMD for doing a right and proper PSU calculator.

C'mon! Zippy has one but you need to supply your own load figures for each output.
 

jonnyGURU

Moderator <BR> Power Supplies
Moderator
Oct 30, 1999
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Originally posted by: tcsenter
....the user has no way of knowing which connectors are loading which +12V output.

Then they need to do some simple reading. It's been common practice for some time to put CPU on one rail, Molex and SATA on another, and put PCIe on their own rails. This completely eliminates the user's need to know what connector goes where. They can plug into any Molex and it's not going to matter because that Molex is on the same rail as any other Molex. Only if they were using something very power demanding, like multiple thermoelectric coolers, are they going to potentially overload that rail.

In your example, you're using a dual +12V rail design. These are ALL CPU on one +12V rail and everything else on a second +12V rail which I admit is completely inappropriate for anything other than a single graphics card build. But almost anything over 600W that has multiple +12V rails has four or more +12V rails, so again.. this isn't a problem. You'll note anything certified by Nvidia recently (G80 and up) has had to have the PCIe connectors on their own rail or it doesn't get certified. That means CPU on one rail to please Intel, PCIe on a second or third rail to please Nvidia and Molex and SATA on yet another rail, so no problem. As it relates to Antec (since the OP is an Antec rep), all Antec PSU's are currently either single +12V rail (although many are labeled as three, the Seasonic built ones are actually a single rail) or four +12V rails (the Signature and TPQ's). So your example doesn't necessarily apply to the OP (maybe the Basiq? But those are all lower wattage units that I wouldn't recommend for SLI, Crossfire or someone cooling things with TEC's, etc.)

Originally posted by: tcsenter
This problem was partially addressed by EPS/SSI that requires some power connectors to be sourced from particular +12V outputs.

No. The problem was COMPLICATED by the EPS/SSI because the specification didn't give a specification as to where to put the PCIe connectors. This is why very early "high performance" PSU's with four +12V rails, like the old PC Power Turbo Cools and the SilverStone ST60's, etc., had problems with high end systems. They would put the 24-pin on one +12V rail, each CPU core (via 2 of the +12V pins on an 8-pin CPU power connector) across two rails and everything else on a fourth rail. This gave multiple +12V rails a bad name early on. SilverStone learned from their mistake and re-arranged the connectors accordingly (as stated: put CPU back on one rail and move PCIe off onto it's own rail) and virtually any quad +12V rail PSU made today is done like this now. PC Power went to single +12V rail. Others followed suit either one way or the other, but don't credit EPS/SSI for addressing the problem when you could say they actually may have caused it.

Originally posted by: tcsenter
But there is still real potential for blind loading assumptions to happen because no PSU manufacturer has taken initiative to plainly disclose how ALL power leads are distributed between the +12V outputs. Will Antec be a leader on this or just another cow in the herd?

No PSU manufacturers? Really? That's a bit of a generalization isn't it? Almost any wiring diagram I've seen for almost any PSU labels the wires (+3.3V, +5V, etc.) and label the +12V as either +12V1, +12V2, +12V3, etc. I would say "no PSU manufacturers." I would say "some PSU manufacturers".

And besides, what is really "blind loading". It's not like a user can take something off one Molex and put it on another to load a different rail. All of the Molexes are going to be on the same +12V rail. The only reason they're going to overload the rail is if they're using a couple Molex powered thermoelectric coolers and the only way they're going to address the problem is to void their warranty and modify a connector on another rail to work with their TEC. But this user is the exception and not the norm and probably (hopefully) smart enough to figure out what's going on if they're PC suddenly shuts off during heavy use. Then again, this user could be one of those bone heads that thinks that multiple +12V rails causes artifacts in Vantage or that higher voltages means better voltage regulation and better overclocking. Some people you can never educate. ;)

 

tcsenter

Lifer
Sep 7, 2001
18,356
263
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Originally posted by: jonnyGURU
In your example, you're using a dual +12V rail design. These are ALL CPU on one +12V rail and everything else on a second +12V rail which I admit is completely inappropriate for anything other than a single graphics card build. But almost anything over 600W that has multiple +12V rails has four or more +12V rails, so again.. this isn't a problem.
It is true, I was making overly broad generalizations based on a much more limited subset of PSUs. My bad. I was speaking largely to mid-range ATX12V designs between 300W ~ 600W, not over-priced EPS12V 600W+ units that provide far more +12V output than would be required by 99% of configurations they are going into.

So your example doesn't necessarily apply to the OP (maybe the Basiq? But those are all lower wattage units that I wouldn't recommend for SLI, Crossfire or someone cooling things with TEC's, etc.)
I wasn't required to limit my examples to Antec PSUs, since the statement about +12V rails to which I replied was a general one not limited to Antec PSUs.

No. The problem was COMPLICATED by the EPS/SSI because the specification didn't give a specification as to where to put the PCIe connectors.
Actually, it did. EPS12V 2.0 and 2.1 provided for an Optional Workstation Power Connector, but nobody implemented it because PCI-SIG did not approve any standard or guidance for aux. PCI-E power until more than one year after EPS12V 2.1 was released. Once PCI-SIG finally released aux. PCI-E power standard, it was folded into EPS12V starting with V2.8 and specifies the configuration.

This is why very early "high performance" PSU's with four +12V rails, like the old PC Power Turbo Cools and the SilverStone ST60's, etc., had problems with high end systems. They would put the 24-pin on one +12V rail, each CPU core (via 2 of the +12V pins on an 8-pin CPU power connector) across two rails and everything else on a fourth rail. This gave multiple +12V rails a bad name early on.
No, multiple +12V rails received a bad name due to the ATX12V 2.x specification that first required 240VA compliance, a couple years before non-server EPS12V PSUs appeared on the market. Criticism of split rails almost universally cite the ATX12V 2.x spec as the impetus. It was EPS12V that rendered this criticism largely irrelevant. If a few early EPS12V units were poorly designed, that doesn't reflect on the spec. Lots of others managed to get it right, PCP&C Turbo-Cool and Silverstone ST60 were the exception.

SilverStone learned from their mistake and re-arranged the connectors accordingly (as stated: put CPU back on one rail and move PCIe off onto it's own rail) and virtually any quad +12V rail PSU made today is done like this now.
I agree. They looked at the numerous others who managed to get EPS12V right and followed their example.

No PSU manufacturers? Really? That's a bit of a generalization isn't it? Almost any wiring diagram I've seen for almost any PSU labels the wires (+3.3V, +5V, etc.) and label the +12V as either +12V1, +12V2, +12V3, etc. I would say "no PSU manufacturers." I would say "some PSU manufacturers".
Again, I was largely speaking to ATX12V units, for which hardly no one provides the wiring break-down. You are correct most are providing it for EPS12V units.

BTW, Antec does not provide wiring diagrams, even for its EPS12V units. At least, none that I can find on its website.
 

jonnyGURU

Moderator <BR> Power Supplies
Moderator
Oct 30, 1999
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tcsenter: I wouldn't say the TurboCool and ST-60 were exceptions since they were arguablly the first PSU's on the market to utilize multiple PCIe power connectors on a quad +12V rail platform.

As for the Antec wiring diagrams, you're correct. All of the Seasonic built units say they're three +12V rail when they're really just one. The Enhance built units you can get wiring diagrams from Enhance. The Delta made Signatures are not diagramed, but I would suggest to Antec that they should be.

I asked AntecRep to "unbrand" the post so it could be stuck as an FAQ. He has and it can be found here: http://forums.anandtech.com/me...id=84&threadid=2260432

This thread will be now be locked as a duplicate post.

Thanks!