New PC Power and Cooling Myth!

[jonnyGURU]

Myth #8:


ARE MULTIPLE 12-VOLT RAILS BETTER THAN A SINGLE 12-VOLT RAIL?
With all the hype about multiple 12-volt rails (ads claim that two rails is better than one, five is better than four, etc.), you’d think it was a better design. Unfortunately, it’s not!

Here are the facts: A large, single 12-volt rail (without a 240VA limit) can transfer 100% of the 12-volt output from the PSU to the computer, while a multi-rail 12-volt design has distribution losses of up to 30% of the power supply’s rating. Those losses occur because power literally gets “trapped” on under-utilized rails. For example, if the 12-volt rail that powers the CPU is rated for 17 amps and the CPU only uses 7A, the remaining 10A is unusable, since it is isolated from the rest of the system.

Since the maximum current from any one 12-volt rail of a multiple-rail PSU is limited to 20 amps (240VA / 12 volts = 20 amps), PCs with high-performance components that draw over 20 amps from the same rail are subject to over-current shutdowns. With power requirements for multiple processors and graphics cards continuing to grow, the multiple-rail design, with its 240VA limit per rail, is basically obsolete.

PC Power and Cooling is once again leading the industry. All of our power supplies now feature a large, single 12-volt rail. The design is favored by major processor and graphics companies, complies with EPS12V specs (the 240VA limit is not a requirement) and is approved by all major safety agencies such as UL and TUV.


Interesting how PCP&C had a change of heart (1kW changed to a 1kWSR) and then decided to write a "myth" about it.


What's funny is the second paragraph. The power is "trapped." As if it were "unusable." Umm.... That's assuming that the rails are actually additive!

I'm just FLOORED with the misinformation here! The only way the power would be unavailable to the other rails is if the total combined wattage of all of the rails were greater than all but one!

They are correct about the potential for any one particular rail getting overloaded and therefore tripping the PSU if the individual rails had a 20A limit, but PSU's with four or more +12V rails don't tend to have this problem because the graphics cards are on their own rail, or rails, so this isn't a problem. You'd typically only see this on a PSU with two or three rails because the graphics cards are forced to share with peripherals.

[syne_24]

hehe..yea i never trust PCP&C in the first place anyways. And now that Silverstone came out with the OP1000, I really dont see anything else PCP&C have to offer. Everything in between you can get it elsewhere for cheaper and better. I have a feeling pretty soon they are going to break their myth about modular psu and make one too. ;)

[madmat]

They have to create marketing hype to "spin" why they have the better PSU since their PSU's typically out price their competition. Gotta justify that price difference. Now if they sold their units for a more realistic markup they could relax on the hoopla and just give straight facts as to why you should buy their units over brand "X".

[Spectre]

Pc Power and Cooling....meh

[DvBoard]

Is there any disadvantage to having a single rail instead of dual or more? To me more than one rail just seems useless...

[Spectre]

Is there any disadvantage to having a single rail instead of dual or more? To me more than one rail just seems useless...

It can be. The point of multi 12v rails in the origianl eps spec was to seperate highdraw loads from one another.

[madmat]

The only real advantage to the multi rail spec is that is prevents any one rail from drawing over 240VA (for 12V that's 20A) per rail. Come to find out, in certain EU countries, to install a device of over 240VA you need a certified (licensed) electrical engineer.

[EsaT]

Come to find out, in certain EU countries, to install a device of over 240VA you need a certified (licensed) electrical engineer.Now what might be that country?




PS. What's wrong in 12V distribution?
http://www.bjorn3d.com/read.php?cID=960&pageID=2546

[Pace]

The only real advantage to the multi rail spec is that is prevents any one rail from drawing over 240VA (for 12V that's 20A) per rail. Come to find out, in certain EU countries, to install a device of over 240VA you need a certified (licensed) electrical engineer.

I think you've missread, or somebody has typoed it. I'm quite confident that they mean a device using voltage over 240VAC.

[madmat]

Um, no. I got that straight from the rep at Tagan when they thought I was criticizing them for not having a single 12V rail.

2.12V rail, as you know Tagan is from Eurpoe German. Base on the safety
regulation, each rail can't be higher than 20A due to the safety. 20A x 12V
=240W if you want to install anything over 240W you have to have
certificated engineer to install product for you.

Since the rep is IN Germany I'm sure she'd know the laws there.

[EsaT]

If there would be such law then it would be illegal to use quite many electrical devices without getting electric engineer to plug power cable to socket...

Also funny how you can buy Seasonic S12E+ and M12 PSUs in Germany, they don't have virtual rails and 12V output ranges from 38A to 56A.

[madmat]

There's a big difference between plugging in something like a hair drier (1500W) and hardwiring a heater. According to Seasonic's site the PSU's you listed are advertised as having quad rails so in Germany they don't fall under the same category as a large single rail. Yes they are just a single rail but they're marketed as multiple rails, probably to bypass that very stipulation or due to PCP&C being whiny beyotches about being the only single rail PSU that Seasonic makes.

[Makalu]

wow...if i get a faster cpu will it free up the trapped power that's bottle necking my psu? if i live in germany and have a tagan 2-force do i need to call an engineer to move the switch from dual rail to single? is this a good psu? ((http://cgi.ebay.com/Gold-650W-Max-Silent-ATX-Dual-Fan-PS-w-Multi-Outlet_W0QQitemZ330066149319QQihZ014QQcategoryZ449 49QQrdZ1QQcmdZViewItem

it's single rail and 650w so it should be as good as multi-rail 900w with 30% of the power trapped yes?
;)

[EsaT]

is this a good psu? ((http://cgi.ebay.com/Gold-650W-Max-Silent-ATX-Dual-Fan-PS-w-Multi-Outlet_W0QQitemZ330066149319QQihZ014QQcategoryZ449 49QQrdZ1QQcmdZViewItem

it's single rail and 650w so it should be as good as multi-rail 900w with 30% of the power trapped yes?Intending to participate coming competitions (http://www.jonnyguru.com/forums/showthread.php?t=688)?
I wouldn't expect to get more than 300W out of that except as smoke.


MTBF over 30,000 hours at 25C.
"Standard" is 100 000 hours. Voltages are propably anything between those allowed extremes, 12V output is propably 22A... which is propably also just peak value!
No PCIes, only one SATA...


Okias... That seller really seems to specialize to substandard junk.

[Oklahoma Wolf]

is this a good psu? ((http://cgi.ebay.com/Gold-650W-Max-Silent-ATX-Dual-Fan-PS-w-Multi-Outlet_W0QQitemZ330066149319QQihZ014QQcategoryZ449 49QQrdZ1QQcmdZViewItem


Very, very unlikely.

[DvBoard]

you need a certified (licensed) electrical engineer.

Working on that right now :D. Really i don't see why it's that strict. Your basicly saying there no reason other than "safety" laws that we use multi rails, and to keep on device from pulling amperage from all the other devices?

[Bbq]

Woah, that ebay power supply looks like a fuckin' STEAL. I mean, it's gold, for christs sake. I wouldn't dream of anything even coming close to that bad boy. Etasis? Enhance? Wintact? Zippy? Feh

:lol:

[SKYMTL]

Jonny, Jonny. Now you are NEVER going to get a PCP&C unit to review!!! ;)

Interesting read though....

[Tazz]

LOL he has friends that can acquire things too :D .

[CAD4466HK]

Interesting
I have a client who has also bought into the FUD.
He's insane to think that the Silencer 610 is "the" best bang for your buck PSU:p I heard about this shit from him for months, then he upgraded.
No amount of goading would get him to reconsider the M12 700 or the ST75ZF that I "was" planning on buying for him, for his OC Kent and 8800GTS{non-SLI}8x Raptor 150's RAID0+1+5,eVGA NF68 , Promise card,1xPlextor16x DVDRW,1xPlextor Blu-Ray,2x exter.LACIE Firewire 16x DVDRW{the backup king}Physics card{I know;) }ect., ect........

Now all this shit was so he could perform his daily photo editing job, and some
ESIV:p
Now the heat this rig throws off is intense, wound all the way up{P180}
I "borrowed" the temp laser from work and shot it at the the bottom tier floor,
just in front of the HD cage{where the 120mm use to be}and got a reading of
46C:eek: Bear in mind, this clients "office" is a converted 2-car garage, in the
middle of the day, ambient temps were around 88F{no A/C:eek: }
Now I told the ill-informed client that his case temps would more then likely
kill his Silencer, being as it was only rated for 40C. He just laughed as they always do right before I'm proven right;)
3 weeks later{yesterday} He calls me up and starts spewing out words I haven't heard since jr.high:p
I chill'ed him out, promised to burn with him;) and told him I would be right over.
I arrived to see his rig froze up in the middle of a backup job and the speaker
was beeping over and over and over.
In 3 strides, I was at the PSU switch. popped the side off{as one of the tabs broke:p } and stuck one of my paws in and said; "Fuckin A, that bitch is on fire!!!" or something like that, The Silencer was hotter then the inside of a well diggers asshole. The Silencer still booted up no problem, but.... I could smell
the paint and other componets BBQ'ing and let me tell you all right now, that
Silencer 610 ain't that quiet when it's being slapped around.
So as of now, I've got a ST75ZF on the way,plus now that he's seen and felt
the humilation of having a underspeced PSU, PC Power&Cooling, have yet
lost one more client due to FUD

[Makalu]

Woah, that ebay power supply looks like a fuckin' STEAL. I mean, it's gold, for christs sake. I wouldn't dream of anything even coming close to that bad boy. Etasis? Enhance? Wintact? Zippy? Feh

:lol:

yeah I looked into the other brands you mention but none of them have the 4 AC outlets and 3.3v and 12v connectors on the back like the Gold one....all they have is a stupid metal panel with a bunch of holes in it, probably to save a bit on material cost...cheap stingy actions like that really get on my tits...

[GalvanizedYankee]

Thought: The small ATX pins use in the 4, 6, 8, 20 and 24 pin shells are rated by Molex for 9A continous.
Now I've only seen pics of melted shells. Question to self. Will I see more in the near future with the use of high output single rail PSUs?
A decent tech setting up or maintaining equipment is one thing, a wide-eyed youngster playing with gaming hardware is another. :)
I hope the OCP is always quick to react ;)

[madmat]

Barring a short I really don't see those connections trying to draw more than 9A do you? A PSU doesn't ram current down the throat of a connector, it just supplies what is drawn by the connector in question.

[GalvanizedYankee]

Barring a short I really don't see those connections trying to draw more than 9A do you? A PSU doesn't ram current down the throat of a connector, it just supplies what is drawn by the connector in question.

Excuse me! If you think I am that stupid, ask jonny to ban my account.
Are you stoned, drunk or medicated, to even suggest I believe such a thing?
Maybe this forum should be the exclusive territory of those that do PSU reviews.

I just presented a FACT of Molex spec, that is all!

Did you even read my previous post?

You hot shot ex-spirts are going to get lonely here:cool: Matt I did notice your
forum is like a ghost town.

[madmat]

Excuse me! If you think I am that stupid, ask jonny to ban my account.
Are you stoned, drunk or medicated, to even suggest I believe such a thing?
Maybe this forum should be the exclusive territory of those that do PSU reviews.

I just presented a FACT of Molex spec, that is all!

Did you even read my previous post?

You hot shot ex-spirts are going to get lonely here:cool: Matt I did notice your
forum is like a ghost town.

First of all you suggested it, maybe you should re-read your post. The melted molex shells you speak of are generally a result of the pins becoming wallowed out and causing the pins to not conduct properly thereby causing a draw of more current than is needed. A multi rail PSU won't fix that problem due to just about every multi rail unit being capable of more than 9A per rail. I wasn't being a smartass just pointing out the why of it not being an issue. Maybe you need some medication, booze or a puff on a doob.

[GalvanizedYankee]

Thought: The small ATX pins use in the 4, 6, 8, 20 and 24 pin shells are rated by Molex for 9A continous.
Now I've only seen pics of melted shells. Question to self. Will I see more in the near future with the use of high output single rail PSUs?
A decent tech setting up or maintaining equipment is one thing, a wide-eyed youngster playing with gaming hardware is another. :)
I hope the OCP is always quick to react ;)

I quote myself so you can re-read it Matt.

Intel introduced that spec to protect hardware. Yes I know they have backed away from it.
My original post in this thread stated a fact of Molex spec and wide eyed gaming youngsters. I use Pro-Gold on all connections and never force or wiggle any during a build.

And NO I do not use drink or drugs.

JEDIYoda, any shit stirring post you offer will be deleted :D

[madmat]

I quote myself so you can re-read it Matt.

And NO I do not use drink or drugs.



Maybe you should :P

[GalvanizedYankee]

Maybe you should :P

Way off topic.
The party ended in '82 at age 35 and I'm not going back for love or money!

Properly done, there is no issue with multi-12V rail PSUs.

Many PSUs of the recent past offer 28~35A on the 12V rail and that will offer quite a snap when it hits ground via a short. 50~80A on one rail will melt 18AWG faster than young hands can let go. Yawza!
We will see what happens in the future :)

The sad fact is...PCP&C is using FUD to fight for it's shrinking market share. :cool:

I used to run 4AWG from 150A alternators up into truck cabs so the drivers could use thier kick-ass linears. I've seen what happens when idiot mechanics do not protect that wire from being crushed. 4AWG doen not deal with 4xgroup 4 batteries to a shorted ground very well. I ran 4AWG to both the hot & ground post on the alternator.;) I used two 50A circuit breakers in parallel, most guys never protected the circuit.

[JEDIYoda]

You state-- the sad fact is...PCP&C is using FUD to fight for it's shrinking market share.

To be a fact you have to have dicumentation that is the case...
Without proof then it can be said that what you just stated is your own brand of FUD....

Merry ChristmaS!!

[GalvanizedYankee]

You are THE pcp&c fanboy JY. :D I know the FUD that hurting companies offer. Dodson would do well to stick with the truth rather than inventing his own.

I will not interact with you here JY, or at AnandTech or at Badcaps. You leave a stink where ever you go and never offer any intelligent input.
You should have been ban last month but it was let to slide ;)

[madmat]

The problem with multi rail units though is that the OCP limits the end user to whatever it's set to. Say I decide to build a home fileserver and I've made a killing on older SCSI drives so I've got 18 of them to use in my server. With a multi rail PSU if I set them to all spin up at once I'm going to trip the OCP considering we're talking on the order of 2A per drive. If your controller won't support staggered spin up you're either in the market for one that does or screwed.

A single large 50A rail removes this worry and makes life easier for you and your drives. my only point at the begining of this drama before you flipped your wig was that your post is FUD in and of itself. Anyone reading it that doesn't know better will think "OMG, those little pins only can take 9A and that PSU pushes 50A (or 36A or what have you) so it'll fry them" which is only the case in the event of a short as I pointed out. Yes, you obviously know better and I know that you know better but not everyone visiting this site knows better. There are other brands of single rail PSU's out there besides PCP&C (The 600 EE I reviewed for example) and they're no more unsafe than their multi rail cousins unless they're abused, and anyone abusing a PSU is going to get hurt one way or another eventually.

[GalvanizedYankee]

I fully understand about the loading presented by 18 SCSI drives spinning up at the same time. We are talking apples and oranges. You bring up a server and we were talking a gaming rig. With 18 SCSI drives, does one worry about PSU fan noise? I would think, NO! So a Zippy or SuperMicro SMPS would do fine.
Does every poster have to offer proof of working knowledge? ;)
I have read this pcp&c e-pee-pee FUD for several years now over at Anand's. Thier product is good but over priced for bragging rights, marketing and to support customer service.
Anyone worth his/her salt will read most of the info on jonny's links page...or so I'd think as I have over the years. If they think a 60A 12V rail will hit an ATX pin with full amperage at boot...Well, they should just buy a Dell. :D

[madmat]

I wouldn't buy a Zippy or SuperMicro or PCP&C for a home file server made up of a bunch of scavenged drives. Not because of noise but because I'm a thrifty bastard. I'd use something like a M12 or the 600 EE or something that won't run me a small fortune. A home server isn't really mission critical.