What Cable is the 12V1 and 12V2 rail?

[soulphie]

Hi guys,

i just have a quick question.

the 12V1 rail on the PSU seen in the picture has 28 amps and the other 22, a buddy of mine wants to get a gpu uses more then 12*22 watts of power but less then 12*28 watts of power under full load and all inefficiencies deducted. So my question is, is the 12V1 rail the CPU power cable or the PCIE power cable?
Thanks for taking the time

 

[LabRat 891]

Hi guys,

i just have a quick question.

the 12V1 rail on the PSU seen in the picture has 28 amps and the other 22, a buddy of mine wants to get a gpu uses more then 12*22 watts of power but less then 12*28 watts of power under full load and all inefficiencies deducted. So my question is, is the 12V1 rail the CPU power cable or the PCIE power cable?
Thanks for taking the time

Good question. In my limited experience, it varies.
The last Delta dual-rail PSU I pulled apart to mod into a bonded rail, was already bonded.
Some PSUs will dedicate a rail to CPU power, and share the other, etc.

Someone more familiar with PSUs can probably give a better, more-solid answer.

 

[soulphie]

oh wow, so there is no standart then?

 

[LabRat 891]

oh wow, so there is no standart then?

If there is, I do not have it memorized.
ATX spec has changed a few times since the last time I 'nerded out' on PSUs.

 

[dirtyferret]

the 12V1 rail on the PSU seen in the picture has 28 amps and the other 22, a buddy of mine wants to get a gpu uses more then 12*22 watts of power but less then 12*28 watts of power under full load and all inefficiencies deducted. So my question is, is the 12V1 rail the CPU power cable or the PCIE power cable?

it's a single rail split

12v1 - mobo, SATA, PCIe-1
12v2 - CPU, PCIe-2

 

[Bill_Bright]

No, there is no standard. Each maker can split it up any way they want.

It should be noted that multirail systems are phasing out because they did not live up to the marketing hype as the marketing weenies had hoped. The better solution turns out to be a single rail where all the produced power is available all the time. With a true multirail system, a percentage of the total produced MUST remain available on the second rail, even if not used. Multirails also adds to the complexity of the design and build - adding to the cost as well as more components mean more potential points of failure.

That said, Be Quiet still uses multirail in some of their systems. And all I can tell from the data sheet and manual for that B9 600 is the same as your label above - that 12V1 supports a maximum of 28A while 12V2 supports 22A. That said, not sure how they do their math because it also says combined, they support 48A and 576W. Why not 50A? Not sure.

Oddly - and disappointedly, I can find nothing in the manual or data sheet to indicate which connector on the PSU supports which rail.

it's a single rail split

Not according to this page. Scroll down about 1/2 way to where it says HIGH PERFORMANCE FOR YOUR SYSTEM and note it says (my bold underline added),

It is equipped with 2 independent 12V-rails

Unless they are lying, "2 independent" is not the same as a single split. And I would not expect Be Quiet, as a reputable company, to lie about such an important technical fact. I am sure it is not totally independent as that means separate transformers too, essentially two power supplies on the same chassis in the same case. So this likely means (or should mean) independent (and isolated) taps on the output (secondary) side of the transformer.

 

[soulphie]

Thanks for the replies guys, i think its fair to say if he spends close to 700 bucks for a new CPU and GPU, he should drop the extra 80 on a new power supply to be on the safe side. I appreciate your time

 

[dirtyferret]

Unless they are lying, "2 independent" is not the same as a single split.

it's marketing BS, no way you are selling a 600w bronze dual independent 12v for that price. If it was a platinum 1600w for $250+ than I would say sure that absolutely makes sense.

 

[Bill_Bright]

it's marketing BS

I don't agree. If not true, then they can be sued and prosecuted for false and misleading advertising. I note that particular model is sold in the EU. They have even tougher consumer protection laws than we do in the US.

If it was from a brand no one ever heard of, I would be suspicious. But Be Quiet is a well known, reputable brand.

The fact it is Bronze simply means they can use less expensive parts. And the less than stellar reviews I am reading suggests they did just that - but also confirm the dual rails too.

 

[freeagent]

I used to have an Antec NeoPower 480.. I popped one rail and had to limp my system pretty hard till I could afford a new PSU.

Sounded just like Steve's video with the Gigabyte PSU exploding.

1 big massive rail to take everything out properly, don't half ass it

 

[dirtyferret]

I don't agree. If not true, then they can be sued and prosecuted for false and misleading advertising.

that would be tough but I would say I'm 99% sure a budget PSU is not using a more complicated design in platform and parts when it's competing against lines like the Corsair CX series. That specific unit is the B9 version. I know the U9 version was an old CWT platform for the time (double forward design with DC-DC for secondary). That design was single rail split. The B9 I want to say is a FSP raider which was also single. This is not the first time brands said their units were 12v dual rails, Seasonic infamously had this issue on some of their S12ii/M12ii units.

from JG on 12v single vs 12 multi
In most cases, multiple +12V rails are actually just a single +12V source just split up into multiple +12V outputs each with a limited output capability. This is what "OCP" is. "Over Current Protection". It's a protection in the PSU's housekeeping IC that shuts off the PSU when a pre-defined amount of current is exceeded.

There are a few units that actually have two +12V sources, but these are typically very high output power supplies. And in most cases these multiple +12V outputs are split up again to form a total of four, five or six +12V rails for even better safety. To be clear: These REAL multiple +12V rail units are very rare and are all 1000W+ units (the original Corsair HX1000, Enermax Galaxy, Topower/Tagan "Dual Engine", Thermaltake Tough Power 1000W & 1200W, for example.)

Is it true that some PSU's that claim to be multiple +12V rails don't have the +12V rail split at all?

Yes, this is true. But it's the exception and not the norm. It's typically seen in Seasonic S12/M12 based units (like the Corsair HX520 and HX620 and Antec True Power Trio.) It's actually cheaper to make a single +12V rail PSU because you forego all of the components used in sensing current, splitting up and limiting each rail and this may be one reason some OEM's will not split the rails, but say they are split. Some system builders adhere very closely to ATX12V specification for liability reasons, so a company that wants to get that business but also save money and reduce R&D costs will often "fib" and say the PSU has it's +12V split when it does not.
Why don't those PSU companies get in trouble? Because Intel actually lifted the split +12V rail requirement from the ATX spec. It's now "recommended" and not "required".

 

[anonuser57]

It doesn't matter which rails is which. Use two PCIe cables together and you won't have an issue.

 

[Bill_Bright]

@dirtyferret - I hear what you are saying but once again, reviews of that model don't support your claims. That PSU is among Be Quiet's lower tier lines. It also is not the latest designs. Yes, it is from FSP but that does not prove it is single. FSP is an OEM. Yes, some OEM supplied units are simply rebranded. But OEM makers are also used to make supplies designed by the brands. So there is nothing to suggest just because FSP makes it, that it is FSP's design, or a rebranded FSP - it could very well be a hybrid, FSP design with Be Quiet modifications.

If you can find a review that disclaims Be Quite's claim, then I will reconsider.

I am afraid you are making a mistake by assuming two things. (1) That a dual rail PSU cannot be made for a lower cost. They can - though the quality would reflect that - as the reviews suggest. And (2) That dual PSUs only come in top tier lines. Also not true.

 

[dirtyferret]

reviews of that model don't support your claims

which reviews? I've never seen a review for a B9 and like I said, would be shocked if it was since they would be selling the unit at or below cost.

assuming two things. (1) That a dual rail PSU cannot be made for a lower cost.

I know this for a fact

And (2) That dual PSUs only come in top tier lines

not lines, never said that. They come in top wattage units where it makes sense to implement that platform