Are Multiple 12-volt Rails Better Than A Single 12-volt Rail?

[curt]

hey

ok at first i thout dule 12v line psu.s had the 2-4 12v lines conected some where to give u an evin 40 amps boy was i rong

i have a antec sp-500 12v rail 1 runes everything but the p4 lil square plug an 12v rail 2 runs the p4 plug wich i think is kinda dumb what if the board u run dun have that lil 4 pin plug then 12v rail 2 is use less so i hard wired them together in side i know the psu works but havent tryed it on a comp yeat

so now both 12v rails run together

my main system is still quite happy running my enermax 460 single 12v line at 33amp with 3 hd.s 2 raided an a 12amp 7800gs

i allso know some psu.s ar well smart like my enermax

if your sittin in windows doing nothing the volts look kinda low

like
11.83v
4.85
3.1
but once i fire up a game it jumps an steays steady
12.30
5.18
3.35

 

[freaksavior]

4 psu 2 with 1 12v rail, 1 1with quad and 1 with dual ok so there all about the same except for the 12v rails. i was told i should get the SILVERSTONE SST-ST56ZF, but eventually i will go a dx10 graphics card, and don't want to get another psu when that happens. SO, now after posting this topic i dk which one to get.....

 

[curt]

hey

ok the antec 500wat that was modded so both 12v rails run together an its running this comp im typeing on no more noise from the psu playing games an dosent seam to be struggeling to run it any more yay

just dont buy a 25 doller 500wat lol that a givin

just get a half desint name brand one an u should be ok like i sead my enermax is a true 460wat has run every thing i throw at it so far an the one i had before this was a 435wat lasted 3 years till my water cooler driped some condesation on it only prob i ever had was when it got dirty shut off an wouldent come back on cleaned the psu an it was fine

i only recomend the older dell psu.s if u plan to run 2 psu.s in total cus alot of the dells an compaq psu.s have volt ajusters in side oh what fun for your mobo some of the newer ones do this antec does not neather does my ener max

but when its only the board running off the modded dell one i get some nice oc.speeds

thers one they sell like that to its like a 600w with ajusters far all the rails sepritly but was high $$

lol this psu i got frm a dell the one this comp was runnen on is a hipro 253m/n 250wat 12v rail reated at 14 wats an runs this comp fine evin with my power suckin ti4200 on the mobo

now the antec is rated at 17a on 12v rail one y was it havin ishews when a 14a psu from 1998 newer tech amazes me is the sadest ways some times

the antec is doing fine with the rails conected thow

i guess that thing u sead about trapped power is true

 

[niko084]

@ Niko084; What do you think of I STAR PSU's?

After reading a bunch of reviews on them, and looking further into them and the kind of business they do. I get the opinion they make a very rock solid, stable, great output power supply. They are very bland and boring looking, but according to everything I came by they are just amazing in output and stability.

Note- People say they are pretty loud....

Remember they make a lot of their stuff for servers, so loud isn't a problem to them. I can't say how loud personally I have not had one, but people say they are pretty loud.

 

[niko084]

Niko if you had read what i said, and done some extra research you would have disproved your own post. there are very few power supplies with multiple generation circuits, mutli-rail psus are single rail with power sectioned off so no one part can draw enough to melt the wiring. if the voltage on one rail drops so does the other, aka how dual/tri/quad rail psus have been proven a hoax.

if they were all true multi rail and you plugged two different rails into say an 8800gtx, the different voltages would end up shorting things out.

to this day the only way they can fit dual/tri/quad power conversion circuits into one casing is by making it larger and packing it full. no cheap light psu will be dual rail, just seperated circuits.

finally it is a better design yes, in theory. it was simply made by intel due to their high draw pentium ds and presscots. they wanted to be sure they would not overdraw any one wire and melt the harness (which has happened a time or two). it is simply a limiter of a bunch of wires/a trip point per say. if the current goes over that trip point the psu shuts off to make sure nothing will start melting.

atx12v is just a cop-out for psu manufacturers so they can use cheap smaller gauge wire. this is non-issue with higher end parts but the higher end is a small margin compared to big box workstations and home pcs.
@GLD - which one of these is a $100? http://www.newegg.com/Product/Produ...&Subcategory=58&description=&Ntk=&srchInDesc=

Ohh okay here I see what you are saying now.

Now that is true, I was tired and mis understanding half the things I relying to over the last few days.. And that is another thing you do have to look at is if the psu is true fully supported multi rail or not.

 

[niko084]

4 psu 2 with 1 12v rail, 1 1with quad and 1 with dual ok so there all about the same except for the 12v rails. i was told i should get the SILVERSTONE SST-ST56ZF, but eventually i will go a dx10 graphics card, and don't want to get another psu when that happens. SO, now after posting this topic i dk which one to get.....

That 56f is not a very hot psu....

Any of the other 3 should be more than sufficient for a single 8800.
As long as you don't run 4 hard drives at 15k, overclock like a crazy man, and use 8 sticks of ram.

 

[EastCoasthandle]

I wonder if half the people who spout their unfounded knowledge of mutli-rail power supplies have actually got a meter out and measured their components under loads.

Niko, Mgrant?

I don't know where YOU got the info, but I think you should try a few hardwire-on-hand tests. There is no such thing as true combined multi-rail amps, it's still coming from the same power source; there are a few companies that have a 'combining' architecture that supposedly meshes the rail amperage together when required, but the efficiency is awfully low, it's unstable, and it doesn't give you twice the amperage(or three times/four times etc), rather it's 20A+20A = 30 or 31A; you lose power efficiency in the process.

If I'm not mistaken your PSU model and it's similar product line are four rails rated at 12v each, not 12/12/18/18. The "62" amps they speak of is maximum overload, not maximum safe excluding overhead. And the funny part is, in your decision to make up the number for the third and fourth rail of your model you must have miscalculated because you left out to 2amps; unless of course you were being conservative for overhead purposes


The rule of thumb is, (and especially for gaming) mutli-rail PSU is a hoax.

Intel was forced to put time into safety technology and then later pulled their findings, admitting that multi-rail power supply was essentially pointless.

Unfortunatley by that time, two years had passed and the market had been bloated with this 'new' technology for PSUs. Even more unfortunate, it became so believed by the masses and computer geeks alike, that companies are STILL getting away with pulling the wool over consumers eyes, by marketing super hyper flashy high wattage ATX 2.2 units.

It's no coincidence that it's difficult to find single rail units supplying over 20 amps to a single rail. Fortunatley, some higher end, or oddball companies are retreating from the saturated multi rail market and are offering up the power that we actually need.

Niko I think you reading 900 pages is what's gotten you confused, like countless other unknowing people. If you'd just found one page, the first page, with the right information you're brain wouldn't hurt as much


Whoever said multiple GPU with a multi rail PSU made me almost choke. I wouldn't even dare try that. Personally I don't see how other people can even sleep at night, risking running $1,000 worth of GPU cards on such horrible power supplies.

You get a big damn case and mount two single rail high amp units.


The thing that ices the cake, is that because of this market, the companies that sell these products don't give you the most vital information : the amps on the 12v rail.


Freak, if you are only using one late modern GPU, then a 550-600 watt 34+ single rail PSU will do you and your other components fine. Fortunatley you can get one for about $100-120 USD, from a Tier 1 quality manufacturer such as Silverstone.

Or you can pay $250 + for some absurd 800 watt that will never fully power your card.

I'm quoting this again so people can read it. This person tells the truth of the matter. To sum it up muti rail psu's are bullcrap!!!

It's amazing how no one offers a thank you or rebuttal to what this person said. And, I believe some of the misinformation posted in this thread needs to come to a stop. It doesn't take much to realize to buy a decent single rail PSU for your needs over a multi-rail psu or a mutli rail modular PSU (I haven't found a single rail modular yet) thats inefficient, over-rated and underpowered with each additional rail installed.

Also note, there is no standard business practice to show you how that PSU performs at around 30C+. Nor is their any labeling of what to expect from the 12V, 5V and 3.3V. Anyone who believes that it's OK to have a psu that's rated at 12V to operate at 11.80V , 5V to operate at 4.80V and 3.3V to operate 3.20V or 12.20V, 5.15V and 3.38V is dilated. Your video card, ram, cpu HD and MB all require specific voltage (optimal voltage) in order to work correctly. That means (unless instructed otherwise, which is rare) if you are required to have 12V, 5V and 3.3V then you need a psu that will provide exactly that. For one, that is why you stay away from modular PSUs (for starters). Secondly, you test this with a multi-meter under load. Third, research reviews for that PSU which provides other important information like voltage performance, fluctuation, ripple, efficiency, etc.

Personally, I've found no manufacture that has come close to PC P&C (based on my needs).

Here is how you check your 12V, 5V and 3.3V

yellow + black 12V

red + black 5V

orange + black 3.3V

This isn't for the inexperienced, you have to know how to operate a voltmeter and you have to know what you are doing when using a voltmeter with live wires, connections, etc. I am not recommending this to those who rarely do this or haven't done this before.

 

[MGrant1957]

If you read my first post....

you would see that the 12v rails are rated for:
12v rail#1 is rated for 18Amps MAX
12v rail#2 is rated for 18Amps MAX
12v rail#3 is rated for 30Amps MAX
12v rail#4 is rated for 30Amps MAX
3.3v rail is rated for 30Amps MAX
5v rail is rated for 30Amps MAX
12v#1+12v#2+12v#3+12v#4 Combined is rated to 62Amps.

Since I have been hand-building Power Supplies for some years, Starting with a MULTI-TAP Transformer that CAN give you multiple 12v rails with a common ground, then run the outputs (Plural) through a full-wave bridge rectifier, followed by the filter capacitors, surge current limiter resisters and voltage regulator/current limiter diodes.

The real limiting factor is the TRANSFORMER.

 

[Wile E]

I'm quoting this again so people can read it. This person tells the truth of the matter. To sum it up muti rail psu's are bullcrap!!!

It's amazing how no one offers a thank you or rebuttal to what this person said. And, I believe some of the misinformation posted in this thread needs to come to a stop. It doesn't take much to realize to buy a decent single rail PSU for your needs over a multi-rail psu or a mutli rail modular PSU (I haven't found a single rail modular yet) thats inefficient, over-rated and underpowered with each additional rail installed.

Also note, there is no standard business practice to show you how that PSU performs at around 30C+. Nor is their any labeling of what to expect from the 12V, 5V and 3.3V. Anyone who believes that it's OK to have a psu that's rated at 12V to operate at 11.80V , 5V to operate at 4.80V and 3.3V to operate 3.20V or 12.20V, 5.15V and 3.38V is dilated. Your video card, ram, cpu HD and MB all require specific voltage (optimal voltage) in order to work correctly. That means (unless instructed otherwise, which is rare) if you are required to have 12V, 5V and 3.3V then you need a psu that will provide exactly that. For one, that is why you stay away from modular PSUs (for starters). Secondly, you test this with a multi-meter under load. Third, research reviews for that PSU which provides other important information like voltage performance, fluctuation, ripple, efficiency, etc.

Personally, I've found no manufacture that has come close to PC P&C (based on my needs).

Here is how you check your 12V, 5V and 3.3V



This isn't for the inexperienced, you have to know how to operate a voltmeter and you have to know what you are doing when using a voltmeter with live wires, connections, etc. I am not recommending this to those who rarely do this or haven't done this before.

Although I know modular supplies are a little more inefficient than standard ones, it doesn't mean they are necessarily bad. mine puts out 12.03v, 3.38v, and 5.06v as measured by the bios.

 

[niko084]

you would see that the 12v rails are rated for:
12v rail#1 is rated for 18Amps MAX
12v rail#2 is rated for 18Amps MAX
12v rail#3 is rated for 30Amps MAX
12v rail#4 is rated for 30Amps MAX
3.3v rail is rated for 30Amps MAX
5v rail is rated for 30Amps MAX
12v#1+12v#2+12v#3+12v#4 Combined is rated to 62Amps.

Since I have been hand-building Power Supplies for some years, Starting with a MULTI-TAP Transformer that CAN give you multiple 12v rails with a common ground, then run the outputs (Plural) through a full-wave bridge rectifier, followed by the filter capacitors, surge current limiter resisters and voltage regulator/current limiter diodes.

The real limiting factor is the TRANSFORMER.

Exactly.

And voltage drops even in the least is not good... If optimum is 12, you should run as close to 12 as possible. Too much you start to have problems, too little you also start to have problems..

There is a part a lot of people don't realize. Everyone knows too much voltage is bad, what they don't realize is even slightly under voltage is bad also, when you under voltage something and it requires more power, it just draws more amps... Thats really bad... It's like when you have a bad alternator and battery in your car and you have to start it on low volts all the time,what happens? Your starter burns out... Now 11.8 compared to 12.0 sure not a big deal there, but enough to drive me nuts personally.

Odd's are on my next psu, I will take it apart and stack it with capacitors to get it as close to perfect voltage as I possibly can. Overkill - yes... But I'm a nut about it and want it as close to perfect as I can get it. I have also been considering building my own psu at some point. There are really a very simple design if you know what your looking at.

Multi-rail, single-rail they both work, they have both existed for a long time, and before the P4s. I'm not saying one is really better than the other. It's more of a choice thing, which one would you like, and whats available.

To put it down simple, either one in a good quality psu will handle anything you can throw at it.

Oh--- My friend has dual x7950s on a 4 rail i-star 750watt, he runs 3 scsi 320 10k drives, optical, fans, basic stuff. He has a e6600 and 2 gigs of ram. Absolutely no issues at all.
4-rail psu rated at 750 watts. So it just goes to show that multi rail can hold it as well. Key being buy a *GOOD* one.

FYI- the 7950s he hasn't tested them pulling more than 4.7amps off the pci-e plug each. So whats the sense in a single rail, when his pci-e plugs can give out 18 amps from their rail?

Well if the 7950 will pull 4.7 and Nvidia says their 8800 will pull 5.5... I don't see any issue coming up here. And thats being realistic. The psu costs about $200 everywhere I find it.

@Namslas90-
Looks like that i-star will do grand! I was talking to him last night and I started talking about power supplies, he said he had it and it ran like a dream. He also said its not really as loud as he thought it would be, but its fairly loud.

 

[niko084]

Although I know modular supplies are a little more inefficient than standard ones, it doesn't mean they are necessarily bad. mine puts out 12.03v, 3.38v, and 5.06v as measured by the bios.

Ya modulars aren't as bad as people make them out to be. The key is being you have the extra connection just to make sure it stays tight. Another trick would be to use a little dielectric grease inside the connections to just aide that much more in current transfer. I myself am ordering a modular to replace my current one with my new system build. I'll post some voltages at idle, and full load after I get it all done.

 

[ex_reven]

small question, someone said something about voltage drops when you have multiple rails

wouldnt a single rail suffer similar problems? I remember being told a while back that if there is an increase in voltage, resistance in the cable increases, which is why at high voltages cables can burn out. Would a multi rail psu reduce this resistance?

 

[quasar923]

do u think that a 750 watt psu with a single 12v rail with 60 amps is good enough for my system:

q6600
asus p5b deluxe
8800gts
dvd burner
250 gig 7200 rpm sata hdd
antec 900 case
cruical balistix 8000 (1000mhz)
and SILVERSTONE DA750 ATX12V / EPS12V 750W Power Supply 100 - 240 V
http://www.newegg.com/product/product.asp?item=N82E16817256017

 

[Wile E]

do u think that a 750 watt psu with a single 12v rail with 60 amps is good enough for my system:

q6600
asus p5b deluxe
8800gts
dvd burner
250 gig 7200 rpm sata hdd
antec 900 case
cruical balistix 8000 (1000mhz)
and SILVERSTONE DA750 ATX12V / EPS12V 750W Power Supply 100 - 240 V
http://www.newegg.com/product/product.asp?item=N82E16817256017

That psu is more than enough for what you have. Hell, you could run a 8800GTX SLI setup on a 60a psu.

 

[MGrant1957]

Does anybody out there listen to an electronic engineer?

PC Power and Cooling does make very good single-rail Power supplies. However, that does not mean that modular systems are junk. any good power supply will have full-wave rectification. several large capacitors for filtering the output of the rectifier, surge current resistors, voltage clamping diodes, power-factor correcting capacitors/inductors, and regulator circuits to keep things in line. the real limiting component in ANY power supply is the transformer, be it a single-tap or multi-tap. a single transformer can have dozens of taps , each one giving a different output voltage. if the Primary coils (ie 120v side of the transformer) are of a sufficient gage, and the input power cord as well, then it can supply enough magnetic flux density to power anything you can through at it.

 

[tkpenalty]

Hell you could run a 8800GTX SLI setup on my iGreen without a problem.

 

[KennyT772]

Does anybody out there listen to an electronic engineer?

PC Power and Cooling does make very good single-rail Power supplies. However, that does not mean that modular systems are junk. any good power supply will have full-wave rectification. several large capacitors for filtering the output of the rectifier, surge current resistors, voltage clamping diodes, power-factor correcting capacitors/inductors, and regulator circuits to keep things in line. the real limiting component in ANY power supply is the transformer, be it a single-tap or multi-tap. a single transformer can have dozens of taps , each one giving a different output voltage. if the Primary coils (ie 120v side of the transformer) are of a sufficient gage, and the input power cord as well, then it can supply enough magnetic flux density to power anything you can through at it.

Nothing against you man, but you are trying to explain japanese to a 4 year old. Few of us know the exact nature of power supplies, we just know what setups are used and how they output power. If you can break down the key difference between single tap/multi tap we would understand more and be able to give comment.

I do know that for the cheaper "uber high wattage" power supplies they often use cheap caps, and a single transformer. The high end 1000w-1200w psus I've seen have had large and multiple transformers, usually one for the 5v/3.3v/etc and one or two for the 12v lines. From there the lines are seperated out by fuses to prevent overload etc.

 

[Dippyskoodlez]

Everyone always points to that article, but they never seem to realize that it is posted on the website of a company that builds power supplies.

I disagree with the majority of what that site says, IMO it creates more bad myths than it actually addresses.

ANd the little fact you leave out, is that its posted on the company that makes the uncontested best PSU's available.

I Have one. You may say Bias, but This thing is amazing. (Yes, I have used a powerstream to compare this to. its just no contest in quality)


The only reason I would really see going multi rail is to save money.

I don't see any BENEFITS to doing it.