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All else equal, ire more +12V PS rails better? How?

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February 16, 2010 4:37:44 AM

Are many +12V rails better than one?

I want the most reliable and quiet PS for a 1366/SLI system ... I want at least 750w and MANY SATA connections ... All else equal, What does the number of +12 Volt rails have to do with performance under load?

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February 16, 2010 5:32:53 AM

Not necessarily...
A single 12V rails would be more advantages as you dont have to worry about load balancing across the multiple rails...
The 12V rails are important as they only provide the power for the Graphics card and other peripherals...
IF you want a good 750W PSU, then get them from any of these manufacturers -
Corsair/ Antec TP, Antec EA/ PCP&S/ Silverstone/ Seasonic/ CM Real Power, Silent PRO...
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February 16, 2010 5:43:15 AM

I suspected such, as some of the most feature rich (and Gold Rated) PSs only sport a single +12V rail, While some of the obviously crappier generic units may sport as many as 6 rails. Very interesting ... I wonder what those taps look like on the schematics and what sort of "zener" regulation the better (server class) PSs employ. Have not ever seen any articles which speak to this ...

... anybody else heard naught about the number of +12V rails, in quality PS design?

(P.S. I am doing this research cause I am waiting on GulfTown, SATA-III, USB3.x and (hopefully) a zippier (PCIe3.x) bus interface ... I even have to wait for cases to employ USB3.x !!! So, I am just trying to find a very quiet, enterprise quality, SLI/CX that can push a big rig in a sound studio (sometimes) environment.

Thanks, in advance.
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February 16, 2010 5:47:05 AM

as Gkay said, a single rail is more convenient since you don't have to worry about a rail failing to supply enough amps (like a GPU with a 30a requirement, when you have 18 amp rails)

but with a single rail, if it fails then you pretty much need a new PSU. whereas a single fried rail out of 6 isn't so big a deal.

in reality though, o think you should always try to get a single 12a rail PSU.
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February 16, 2010 6:52:40 AM

@Alvin Smith not all multiple 12V rail PSUs are crap...You do get very high quality ones with multiple rails...
Antec TPQ Series, Antec Signature and many Silverstone ones have multiple Rails and are of very high quality...
So you dont have to worry much about the Rails if you are buying a PSU from Tier 1 manufacturers...Just read the reviews to see how they perform...
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February 16, 2010 7:16:11 AM

Wow, welsh's post is more or less crap. Remember that a "multi rail" PSU comes from a single source just like the single rail PSUs. In fact, there really isn't much of a difference between them. Get a good one, don't worry if its multi rail or not. There is no such thing as trapped power, nor are single rails better then multi rail.
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February 16, 2010 11:55:51 AM

Most multi-rail PSU's under 1 kw are actually single rail anyway. A good way to check is use an ohmmeter and check for continuity between any two yellow wires.

I suspect that manufacturers claim multiple rails for two reasons. First there's the "Oh, wow. Four rails!!" advertising claim.

Second, it's a way of claiming the PSU meets the ATX 2.XX specifications. One part of the specs say that each rail can have no more than a 20 amp output (I think).

So, technically, the single rail Corsairs (my favorites - I have three) violate the PSU specs.
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February 16, 2010 10:37:01 PM

WOW! Fantastic ! I just want a quiet PS with all the power and connectors that I may ever need, for any future upgrade. While quad SLI is an unlikely "end", for me, I still would like the option ...
... Y'know?, ... EVGA "Top Secret" 4x SLI motherboards often come with combo and kit deals ... some of which may include the appropriate PS for a maxed out extreme SLI/x-fire rig ... I might look there, first, for compatibility/expandability and then check the reviews, etc., for assurance.

Hey, Everybody !? . . . check this awesome primer on multi-rail PSUs, posted by coldsleep ! Very cool! Very authoritative and comprehensive. a great read.

http://www.jonnyguru.com/forums/showthread.php?t=3990

=Al=
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February 16, 2010 10:41:58 PM

4745454b said:
Wow, welsh's post is more or less crap. Remember that a "multi rail" PSU comes from a single source just like the single rail PSUs. In fact, there really isn't much of a difference between them. Get a good one, don't worry if its multi rail or not. There is no such thing as trapped power, nor are single rails better then multi rail.


in a virtual multi-rail PSU this would be true.

but in a genuine multi rail PSU, they are distinct, separate rails.
granted, there are very few PSUs like this, but i think you should have a little look before calling my reply 'crap'.

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February 16, 2010 11:18:23 PM

Fine, then for 99% of the PSUs out there your post was crap/wrong. Happy?

OP, I assume you have your answer?
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February 16, 2010 11:35:28 PM

Dear "Potty Man",
I'm guessing 99% of your posts are just to diss other people's efforts to help ... Am I wrong? Check out your own signature!

I started this thread because it is a VERY good question and, even with ALL the good info from that forum post, it is still a fuzzy decision ...

As for me? ... I think I'll go the single rail route, but look for the mostest connectors and the best efficiency ratings ...

Is my question answered? ... Mostly. I think there should be a 2x/yr roundup of SLI PSUs, which specifically test for 1)Quality of filtering 2)Actual sustained/stable output, under max-typical load ... and ... PLEASE ... 3) PSU audio noise, in the same test space (accoustic lab conditions), and at max load and outside any enclosure (not in a case).

It really is difficult to make such a choice, based on no clear standards for acoustic noise (and testing) ... Looking at the gutz can say a lot ... guage of wires, fan build, solder quality, xformer windings, etc.

Good thing I have until August, to get up to speed ... I am starting with the PSU (for this 1366 build) because it is the slowest moving of all targets. Even some case companies are (now) touting USB 3.0 case connectors ... is there any difference?

Aha! ... new thread!
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February 16, 2010 11:48:08 PM

You'd guess wrong. I do get passionate when incorrect information is presented. Crap is the wrong sorry word, I'm sorry.

When looking for a PSU, I usually select the following (in order) from PSUs I can afford. Efficiency, Available 12V power, and reviews of said unit. The more efficient, the newer the PSU. You want lots of 12V power these days. Reviews of the unit including a tear down can reveal things you might not see otherwise. Like suspect capacitors. Because nearly all PSUs these days are single rail units, EVEN IF THEY ARE MARKETED AS MULTI RAIL, it doesn't really matter. Its nothing to worry about, you can buy a single rail and its ok. As Jsc pointed out, he has bought many single rail PSU and nothing bad has happened. I just wouldn't go out of my way to buy one.

Edited apology.
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February 17, 2010 12:49:28 AM

Didn't mean to get "snippy" ... have run into some really "bad players", out there ... folks who use anonymity just as an excuse to be ugly, or a bully. Culture poison, those cats are! (my best "Yoda")

=Hell, No! ... my first name ain't "Alvin" and my last name ain't "Smith" ... just a nice, nerdy name ... you should picture a clean cut introvert, with glasses. =
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February 27, 2010 12:39:29 AM

Best answer selected by Alvin Smith.
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