Re: single or multiple 12V rail

[ThunderRd]

I've got a new PSU here from Tagan that has a switchable feature that will combine 6 12V rails into a single, high amperage rail. The single-rail mode is called "Turbo".

http://www.overclockersonline.net/im...900/Output.jpg

Could Gizmo or one of the other Illuminati take a look at this and tell me why I'd want to set it one way or the other?

It is my understanding that this single v. multiple rail controversy isn't always what it seems to be, and is often used for marketing purposes. I've done my homework and have my own thoughts but I'd like a little input from someone more knowledgeable than I am.

[Gizmo]

I really don't have enough data to go on here to provide a good recommendation, so I'll go with my gut.

1. I can't imagine a good reason to need to put 70A on a single 12v rail.
2. there are only two ways I can think of that you could even implement this:
   • If the power supply is running a single internal regulator for the 12v rail and you have some sort of current sensing on the individual output connectors, you could then do some kind of current limiting that could be switched on and off. However, you are still running a single regulator so it wouldn't make any real difference to the reliability of the unit, although it might provide some kind of protection to external equipment. Switching off the current sensing (fusing) would allow you to then output more current on any single line.
   • If you are running multiple internal 12v regulators independently on each output, then you could gang them all together internally so that you could provide all of your aggregate output power to a single output if you wanted.

Basically, to me this just sounds like a marketing gimmick, as putting that much current across a single output connector is almost guaranteed to cause something to melt within a year or so.

Not to mention the fact that shoving that much current down a single set of wiring is going to result in some significant I2R losses.

[ccperf721p]

I've always preferred single rail PSU's, mainly because I don't know of many "true" multiple rail mainstream PSU's. My other reasons would be that I run my systems heavy on the CPU side of things but tend to stay away from multiple GPU setups, and I have stuck with the two PSU makers that have never let me down, PCP&C and Zippy, both companies utilising a single high amperage rail..

From what I have seen in "most" multiple rail PSU's it allows them run to lesser quality component as it won't be seeing the amperage that a single rail will..

For me it is more a stick with what I know works. I have never had a PSU failure using Zippy or PCP&C

[cloasters]

A PC setup that draws 70 Amps is yet to be built. And I hope one never is!

[noob]

Multiple rails started due to the ATX PSU specification stating that no output should provide more than 240VA, due to fire risks.

3.2.4. Power Limit / Hazardous Energy Levels

Under normal or overload conditions, no output shall continuously provide more than 240 VA under any conditions of load including output short circuit, per the requirement of UL 1950/ CSA 950/ EN 60950/ IEC 950.
—ATX12V Power Supply Design Guide, version 2.2

Thus having multiple rails on the 12V allowed a combined total of more than 240VA. And plugs were grouped for each rail to allow a spread of amperages accross them. Most of these PSU's though have a single high current source, and seperate regulators, and therefore the max total 12V draw is less than the combined max from each rail. More expensive (and the larger) PSU's are completly independent.

Most of the time the switch from multipe to a single rail, means that it is combining the regulators, and drawing current from them semi equally. The advantage of this, is if you have a single component that would normally draw more than the max amps off a single rail wont trip the PSU, but each regulator still conforms to the ATX specs.

The advantages of having multiple rails, is that you can not use 1 or more without having the same effect on efficiency as a single rail, and that the components for any single rail only have to meet a max of 20A for 12V, 48A for 5V and 72A for 3.3V, for which 5 and 3.3 V are typically much less than the max, allowing for smaller components.

[ThunderRd]

So basically, this is not a true 6-rail PS. It's a single-rail supply that, because of the presence of 6 regulators, adheres to a specification. The six-rail labeling becomes no more than a gimmick to announce that "more is better", when in truth most of us with high-end rigs will use it as a combined rail for the overhead it provides. That is pretty much what I had been thinking, and you all have given me the particulars. Thanks.

It's kind of like we always say in high-end audio (my other passion/hobby): Amplifier wattage is king. In well built gear, there is no substitute for it-even though you will rarely, if ever, use it all. It is the overhead that it provides for sudden dynamics that make it desirable above anything else. You will never "blow" a pair of speakers with too much power. You will, however, destroy them in a moment if you attempt to play something at excessive volume without enough power: that is clipping.

[noob]

Pretty much hit it in 1.

While not enough amps may not kill your components quickly, its not doing good things.

[ThunderRd]

I might add that in other areas the same theory works, too, as in: "there is no substitute for cubic inches", ie. it's the size that matters?

Listen up, all you small-block V8 enthusiasts 427s r00l...except for maybe the 454/450 guys..was it LS6?

[noob]

Guy I used to work with had the 440 Jensen Interceptor - bright yellow with black racing stripes.

Me I want an AC Cobra 427

[ThunderRd]

Cobra's nice but I've always been partial to the 'Vettes.

I still have a '68 L88 427/430hp coupe that has been on blocks for years somewhere in the wilds of New Jersey - if I ever figure out how to get it here to Thailand I'll finish the resto. I want to bring it here but it may not be possible. If that's the case I'll have to part with it. It's a fairly rare car so it's still worth good bucks at the vintage auctions.

[PorPorMe]

When I was 16, my dad bought a 65 'cuda 273. He didn't even drive it home.he put it on a trailer, I'll never forget that. He had a shop then and he pulled the engine, balanced, blueprinted, cam, exhaust, dual Hollys and full blown with a Hurst 4 speed. Cream white with a black stripe.
That was the meanest thing.

[ccperf721p]

Originally Posted by ThunderRd

I might add that in other areas the same theory works, too, as in: "there is no substitute for cubic inches", ie. it's the size that matters?

Listen up, all you small-block V8 enthusiasts 427s r00l...except for maybe the 454/450 guys..was it LS6?

Now you did it!

[Daniel ~]

Originally Posted by ThunderRd

Cobra's nice but I've always been partial to the 'Vettes.

I still have a '68 L88 427/430hp coupe that has been on blocks for years somewhere in the wilds of New Jersey - if I ever figure out how to get it here to Thailand I'll finish the resto. I want to bring it here but it may not be possible. If that's the case I'll have to part with it. It's a fairly rare car so it's still worth good bucks at the vintage auctions.

I'd be happy to drive it to Thailand for you! ":O}

[cloasters]

Yarr, after a quick trip across the Atlantic you'd only have maybe 6500 miles to go. All on superhighways, no chance of mishap at all.

[noob]

You may have to look into seeing if you can get it in via a shipping container.

I do quite like the vettes myself, and my sister wants a 69 stingray convertible.

[Daniel ~]

Originally Posted by cloasters

Yarr, after a quick trip across the Atlantic you'd only have maybe 6500 miles to go. All on superhighways, no chance of mishap at all.

Clear sailing as they say!

[ThunderRd]

The problem isn't how to physically get it here - it's the legalities and the taxes that make it difficult in Thailand.

For motorcycles, as an example, it's about a 300% surcharge on the declared value of the imported bike. Then people got clever. They would disassemble the bike in its country of origin and ship it as parts; then assemble it again in country.

Then the customs department got wise to that, and now they levy the same 300% on parts. Cars have a similar rate.

[Daniel ~]

I just remembered I don't have a Lic.! .....

[cloasters]

Does Thailand have a domestic motorcycle industry to protect with these bodacious import duties? Or are they simply greedy?

[noob]

Ouch that is nasty!