Corsair PSUs not really 3 rails?

[Phantoms]

Reading the review of the HX620 at johhnyGURU's I came across this Addendum at the bottom of the reviews last page:

Since the review of this power supply, some interesting observations have been made of Seasonic built power supplies claiming to have three rails.

Below is a picture of the modular interface PCB. This would have you believe that three peripheral connectors and one PCI-e connector were on one rail (labeled 12V3) and the other two peripheral connectors and PCI-e connector were on another rail (12V2.) This would leave one to assume that the 4-pin and 8-pin are on 12V1 perhaps with the main ATX, or the main ATX is on 12V2 with the fewer number of peripheral connectors.

Looking at the Seasonic main PCB inside the Corsair PSU reveals only two rails, labeled 12V1 and 12V2. There is no third rail. This is illustrated well at Hardware Secrets. Although I can not say that these rails are or are not somehow electronically separated in the PSU's circuitry somewhere, I did find that there was no OCP (over current protection or "limiter") on either of these rails as I was able to load any given connector up 30 to 40A with no drop in voltage, system shut down, etc.

So it is my opinion that we essentially have a single 12V rail PSU here. Certainly there is nothing wrong with this given the problems high end video cards have had with getting enough power from a single 12V rail when the OCP is set to the typical 240VA limit. But we do lose the advantages of multiple rails such as protection from damage to one rail from a short on another and the simple "filtration" of noise introduced from one rail to another.

 

[BBowermaster]

This has been discussed here before. Corsair/Seasonic had Intel's approval/blessing on removing the OCP. As the last paragraph said, its because its hard to predict how much current and future video cards will demand in power, so instead of risking overload on a rail, they removed the limiter. Think of it as future proofing.

 

[Phantoms]

I understand that, but where exactly is the third rail in those photos? I only see two.

 

[Bbq]

If you flip the picture backwards, it should correspond with the 3 molexes on the left side and the left pci-e.

 

[Phantoms]

Yes, that's +12v2, and the others are +12v3, but where in the world is the third 12v rail?

It's in the specs:

These are the only two 12v rails I see:

Edit: Nevermind. I believe that the 12V1 rail is actually the MB connector which is not part of the modular hookup. It's got the 24pin, 4 pin and 8 pins all on a regular set of wires coming out the supply. Anyway, now everyone knows where their rails are on these power supplies in case they want to balance their loads.

 

[jonnyGURU]

Anyway, now everyone knows where their rails are on these power supplies in case they want to balance their loads.

What?!?!

THERE ISN'T THREE RAILS so people don't need to "balance their loads."

 

[Phantoms]

What?!?!

THERE ISN'T THREE RAILS so people don't need to "balance their loads."

Thank you for posting Jonny. From reading at your site, I'm considering getting the Enhance PS. It seems to be a quality PS for a decent price.

 

[EnderW]

I still laugh at how 2 years ago or whenever it was, multirail PSUs were all the rage (for some unknown reason) and finally people are starting to realize they're fucking pointless

 

[BBowermaster]

I still laugh at how 2 years ago or whenever it was, multirail PSUs were all the rage (for some unknown reason) and finally people are starting to realize they're fucking pointless

They still have merit, such as short protection and noise filtration, its just the video card manufacturers went out of control with how much modern video cards draw from the PSU.

 

[InCogneato]

so if i buy this PSU i can still do crossfire and have a bunch of HDDs and all that? more rails are pointlesS? can someone explain what rails do what are they for why they exist etc? this is so confusing and i am planning to get this corsair or the 620w corsair but i hope im not limiting myself to anything by doing so

 

[[Spectre]]

You would be best served by reading through the stickies first.

so if i buy this PSU i can still do crossfire and have a bunch of HDDs and all that? more rails are pointlesS? can someone explain what rails do what are they for why they exist etc? this is so confusing and i am planning to get this corsair or the 620w corsair but i hope im not limiting myself to anything by doing so

 

[EnderW]

You would be best served by reading through the stickies first.

stickies?

 

[InCogneato]

You would be best served by reading through the stickies first.

thanks for your informative reply.

i have read through them before and i understand what rails *are*, however i do not understand what rails *do*

example: the point of having more than one rail? does each rail have a limited number of plugs that can be run from it (which would possibly be the point of having more than one rail and which would in turn determine how many devices you can have, like crossfire or whatever)? etc. none of this is covered.

all extra details and info would be greatly appreciated. i also dont mind reading if you can point me to an article that covers this (none of the ones on the sticky do as far as i can see)

thanks!