Dual 12V Lines?

[Thermopylae_480]

Alright everyone. I'm in the market for a new PSU, because my old generic one is causing system instability. Please explain Dual 12V Lines? It seems that it just causes less amperage to be on each 12V line. What is the advantage to this? Does this allow you to get away with less amperage on the 12V line? It won't be for a SLI/Crossfire system if it makes a difference. It'll be for the system in my specs.

 

[JC316]

Dual 12V rails basicly gives you more stability. One rail powers the CPU and the other powers the graphics card. In your situation, it's really won't do a whole lot of good. It dosen't give you less amperage, you add the two together.

 

[INSTG8R]

Well I just bought the new Seasonic M12 600W it actually has quad rails. 18A on each rail with a max of 48A combined Seasonic M12 I very pleased with it and its performance with Crossfire.
I have a Tagan 580W dual rail(20Ax2 38A comb.) that, while was "stable" aftering measuring it with a Multimeter and Everest logging it was getting VERY low in Eversest(12.46!!) and 12.7's on the Multimeter. The Seasonic is rock solid

 

[Protius]

Well I just bought the new Seasonic M12 600W it actually has quad rails. 18A on each rail with a max of 48A combined Seasonic M12 I very pleased with it and its performance with Crossfire.
I have a Tagan 580W dual rail(20Ax2 38A comb.) that, while was "stable" aftering measuring it with a Multimeter and Everest logging it was getting VERY low in Eversest(12.46!!) and 12.7's on the Multimeter. The Seasonic is rock solid

i also got a quad rail OCZ gamexstream 700w with almost the same specs, this sucker's also rock solid even with crossfire and ocing

 

[KennyT772]

multi rail powersupplies are shitty for power users and overclockers. most x1800's draw over 28a from the 12v and the cpus are about the same.

the reason for multi rail psus is the atx12v 2.0 spec which limits 12v amperage to 18a per rail. now with the dual rail psu your system will run better but it is still overloaded. high amperage single rail power supplies will run a system at its tip top much better then a multi rail model of the same wattage.

instg8r do you really think that seasonic is a good psu? day to day output per rail is in the midst of 12a and that is pathetic. i highly doubt 48a is even the norm as i doubt its 576 of the 600 rated watts...

i would personally use the tagan as they are generally higher build quality and most have adjustment for the power rails. i highly doubt it was reading 12.46 or 12.7 as 11.4-13.2 are atx spec... not to mention your pc was logging 1 voltage (12v 1) and you were monitoring the other rail (12v 2)

 

[g12rxz]

va=w

12v * 28a = 336w

336 watts of power from the videocard alone? I find that hard to beleive... especially since systems with x1800gtos and dual core procs and x amount of hd's and cd drives typically run total wattage between 350-400 watts peak.... if what you say is true though to power a 'cpu' and 'x1800gto' youd need upwards of a 600 watt psu.

12v * 18a = 216w (the new atx spec eh!?)
That's actually pretty reasonable, each 12 volt rail supplies 216 watts..... Your average videocard uses around 30-80w, and your x1900xtx uses no more than 120w on peak loads. Most dual rail psu's ship with more than 18a on the 12v rail. I see it between 20-26a on good psu's.

12v * 22 = 264
x1900xtx crossfire 240 watts.

Since you said this wasn't for an sli/crossfire system whether or not you get a dual rail psu wont matter that much, dual rail will just help with stability in the sense that your cpu is eating power off its own line and your videocards and other devices are eating power off their own lines..

 

[Thermopylae_480]

Ok, so let me get this straight. One rail powers the video card while one powers the CPU. In a more classic PSU a single rail supplies both. Since each rail supples power independently, it is not as important that each rail supplies as much amperage as compared to a single rail.

 

[KennyT772]

that is correct

g12rxz the real test is seeing how the powersupply handles the high load on the low amperage line. yes i was incorrect on the power draw. i was under teh assumption that what atitool reports as draw was 12v which obviously it isnt, i see that now.

however what i said still stands true. the atx12v 2.0 standard (and 2.01 ect ect) are all designed with a max amperage per rail. this is due to the high draw on the older atx12v 1.xx psu's as intel was afraid of drawing too much and melting the wires (it has happened). intel is also behind the eps12v standard. that being said dual rail psu's are good..if from a reputable company. dont expect a bargan 12v with 40a shared to compete with a brand name 30a..

 

[g12rxz]

enermax liberty (500w i beleive) pulls 22a on each 12v rail, it may not be spec, but who cares!?! i didnt mean to disprove you or make you defensive, its just 300+ watts for a videocard is a HUGE mis/conception/calculation.

 

[Thermopylae_480]

Thanks guys. I appreciate the help. I understand that so much better now. I really like the OCZ Modstream and I think I've heard Tagan is good, so maybe a Nanopoint? I think I could get away with a 480W considering my current one is a generic 400Watt with a single 17a line. Especially if it's a decent PSU. Any suggestions? I DON'T want to spend more than 100 US dollars if anyone recomends anything.

 

[g12rxz]

id say keep looking, although the modstream would probably fulfill your needs for now, its only 26 amps on its SINGLE 12v rail. the other one i've never heard of, and some companies rate their wattage higher than it should be... so just keep researching, cause it's a learning experience

EDIT:
Heres what I'm thinking about getting instead of the enermax liberty w/ modular cabling.... http://www.newegg.com/Product/Product.asp?Item=N82E16817194010

 

[Thermopylae_480]

I like that Enermax. I've never had any experience with them though, are they any good? I rather like OCZ, FSP, Seasonic, and Thermaltake. Something Modular would be nice though. It would go a long way to cleaning up my case. This Mushkin seems kind of nice. I like their memory, but power supplies? Where is our Mushkin tech rep ?

 

[Azn Tr14dZ]

As this forum states (and a lot more articles on many other sites too), a Single 12v Rail is better than Dual 12v Rails.

Here:
http://www.bjorn3d.com/forum/showthread.php?t=7457

Also, according to the ATX12v Power Supply guide, it states that "+12v2 is for the 4-pin connector, while the +12v1 is the rail found at 24-pin and molex connectors". So, a single 34A on a 12v rail is better than 17A on dual 12v rails. That's at least what many have said, after having searched many sites. But IMO, if it's good, trusted, and well made (like FSP, Tagan, OCZ, Mushkin, and PC Power & Cooling), then go for it whether it be Multi-Railed or Single-Railed.

 

[Thermopylae_480]

Ok then. I've narrowed it down to either the OCZ Modstream and the Mushkin 550200. After rebates both are the same price. So I guess I have to continue the digging into the Dual rail vs Single rail debate and it's conflicting opinions. Thanks for the link AZN. Most of the article seems to be about to over a year old though. Things may have changed? Although the forum posts are more current, and yet again provide conflicting opinion .

 

[largon]

OCZ ModStreams are based on a comparably old design, definately go with the Mushkin.

 

[KennyT772]

i would go with the modstream. a 26a single rail is comparable to dual 16a's as far as reliability.
hell i have a 3200+/1800xt on a tt420 and its 18a rail is solid.

btw largon you are incorrect. i highly suggest you read this whole thread and gain a bit of knowledge.

 

[GLD]

PC Power & Cooling anyone?

 

[KennyT772]

that would be the best choice but the cheapest psu is around 160...

 

[largon]

btw largon you are incorrect. i highly suggest you read this whole thread and gain a bit of knowledge.

Incorrect about ModStream being based on an almost 2 years old design or that he should go with Mushkin?

 

[Azn Tr14dZ]

OCZ ModStream, and all of the other OCZ PSUs are great, since they are being made by FSP, and they're a well known and trusted company. OCZ PSUs are also recommended for DFI motherboards (from DFI Street). Mushkin, as I heard, are also great. You should ask the Mushkin Techs here (like Ketxxx) and ask how their Mushkins are doing.

 

[Tatty_Two]

Spotting this thread is really good timing as my monstrosity blew up tonight and it's only 3 months old! Check my specs for the useless Antec 5ooW Smartpower 2.0. It has (had!) dual 12V rails, I think one at 19A and the other at 18A. I just hope it has not blown any of my other devices. This must have been caused either by too much stress of just a simple malfunction (was not even under load, I was just browsing in internet explorer, smelt a bit toasty for about 3 secs and BANG!) but I do not reckon it has (had!) enough juice in it for my system. I am no expert but as I see it one of the downfalls of dual rail (I am aware of the positives) is that Ok you get one rail specifically for the CPU but the other rail has to handle everything else. As one here has said earlier, I did notice in ATI tool that at idle on only 2D clocks my 1800XT was drawing 10.8A!!! thats obscene so at idle it only left about 7Amps for 2 HDDs, 2 opticals, 5 case fans, 2 CPU fans, a PCI card etc etc, as soon as I go into a 3D game and put her under load that 1800XT amperage has just got to double surely?

I would welcome your comments, suffice to say I am looking for a cheap but temparary (need some more funds!) PSU to last me until the end of next month with either a single rail of 40A+ or dual rails with, well...... LOADS! is there such a thing as a high powered/amperaged PSU?

I can send the beast to Antec who will warranty replace it, but I have to pay for for insured carriage, now we all know the weights of these things so its gonna cost a lot, I dont really see any point because if they give me another I am just gonna do the same unless I e bay that one to offset the cost of a new one. Ohhh and if you can suggest a cheap but powerful temporary PSU for me please bare in mind that I am in UK.

 

[g12rxz]

FYI software voltages arent always correct. If it was drawing 10.8 amps idle... then multiply that by 12... 129.6 watts, thats more draw than an x1900xt which only hits 120w ( 120/12 = 10a ). I see no problem with dual rails at all, because the 12v lines are split voltage wise, but their amps still add and count towards wattage together. Antecs though out of all of the dual 12v power supplies i would trust the least, i know their single rails are fine, but their dual rail models aren't very good. Get something with more amps on each rail, like the enermax liberty if you want modular cabling or the plain looking enermax i mentioned earlier. Like i said before though the amps add which means if your hard drive needs more amps, the power supply, as its supposed to do can accomdate for that (why theyre called switching power supplies). I can understand the need for dual rail, cause with the power hungry systems we have today, a single rail psu with >38 amps on a single 12v line could pose a pretty high risk of fi0r. As for the power coming from dual rail psu's, the voltage difference is about 1 to .25% off their single rail predecessors. As long as you dont buy a crappy dual rail psu, you shouldnt have any problems.

 

[bruins004]

Hey Tatty I would be glad to offer some knowledge.
There has been a huge argument as to if two (or multiple) rails are better than one.
More rails does allow for more stability (less fluctuating of voltage).
However, as it has happened to me and many others, if a rail dies the PSU is pretty much useless which seems to haunt some multi rail PSUs.
Also, if one rail only uses 10A out of 15A that 5A is unused an is not used at all (not even by the other rail).
Single rail PSUs arent as stable, but do offer all of their voltage to the entire computer. Since there is less stability some power is lost.
So there are pros and cons to both.

I would suggest you stick with an OCZ PowerStream 520W. These PSUs are one rail and will def. supply enough power for you without a problem. I believe they went down slightly in price as well (prob. around $70). It will def. supply you with enough power on the 12V rail for your entire system with some room for upgrades. If you have any other questions please let me know.

 

[Azn Tr14dZ]

If you look at some great and reliable power supplies from PC Power and Cooling, the still use single 12v rail.
http://www.newegg.com/Product/Product.asp?Item=N82E16817703005

IMO, if it's a good and trusted and reliable company, I would get it whether it be Dual +12v rails or a single +12v rail.

 

[bruins004]

I would disagree with you Azn.
I have always had to send back my dual rail PSUs (which are Antec) I receive bc one rail is dead. Cant really power anything up with only 19A lol.
I seem to have bad luck with them so I just usually get 1 rail PSUs bc of that experience, but your right there isnt much a difference.