Confused with my psu (Seasonic S12 SS-550HT) rails and connectors

[lejolasho]

Hello,
I have just brought Seasonic S12 SS-550HT. I have found out, that this psu is not the same as retail version, it has fewer cables, everything else is the same.

the list of connectors:

1 x ATX 24 Pin Connector (20+4-Pin)
1 x 12V P4 Connector
3 x Peripheral Connector (those are on one cable and then splitted)
3 x SATA Power Connector
1 x Peripheral to floppy adapter.

my psu actually has +12V1@18A,+12V2@18A,+12V3@18A,+12V4@18A rails and i want to know, which connector is connected to which rail, how much power can be supplied to each connector?

If the connectors were the same as the others, everything would be ok, because on newegg reviews I read, that this psu handles hd4890 pretty whell, which is quite power hungry. (275 watts on load), but what can i do if I decide to buy 4890 too? won't it welt that molex cable?

 

[HiTechObsessed]

The Molex will be on the +12v rails.

Question though, why would you buy a 4890 right now? That's a very old card.

 

[lejolasho]

thanks for reply. I am glad, that the molex will be on the +12V rails, but how much watts can it carry on?
btw, I agree with you, that hd4890 is a way too old, it even does not have a proper driver support, I used it as an example of a very power hungry gpu.

 

[HiTechObsessed]

Gotcha lol

The +12v rails will not trip until one hits 18a, but the power will be delivered across multiple rails, so you should definitely be fine. The max concurrent draw is 41a total, which equates to around 500w. The thing to keep in mind is that a 'rail' isn't actually a power delivery component, a rail is simply a group of traces monitored by a separate OCP circuit.

In short, you'll be fine so long as you aren't trying to do anything crazy on it.

 

[lejolasho]

Ok, thank you, now I can calm down. I have seen many different ideas about this question while googling and was confused.

 

[HiTechObsessed]

Yeah, power supplies are one of those topics that you can't really get all the information you need on them from a spec sheet from Newegg. Like on a CPU or GPU, it's easy enough to figure out an i3 is weaker than an i5, or a 760 is weaker than a 770, but it's not the case with power supplies.

Especially getting to the multiple rails concept. A lot of people say that a single rail is better than multiple rails, which almost always isn't the case. That was true for high-end single GPU setups years ago, but not anymore (on decent enough quality power supplies). On single GPU setups, there's no benefit to single/multiple rails, but on multi-GPU setups, multiple rails is theoretically better, as it provides more points of safety. All a 'rail' does, is trip the over-current protection circuit if the power going through its group of traces exceeds whatever amperage they have it set at.

Again, in short, power supplies are the most important piece to the puzzle, and unfortunately are one of the hardest to decipher. That's why Tom's is here lol