Rails, Pinouts, and Confusion

[For Science!]

Hello!

 

Gonna try to summon @jonnyGURU on this one again. I as usual will apologize in advance if my question is confused and unclear since I feel I do lack some basic understanding to phrase my question properly on this one, but please bear with me!

 

I was working on making some custom sleeved cables for my SF600 power supply which to my knowledge has a single 12 V rail. I have been re-routing some of the wires for cleaner runs. For the sake of illustration, something like below (perhaps not exactly what I did, but in essence correct), where I have changed some wires that criss-cross in the stock cables and straightened them out while keeping the voltage of the cable the same. I have already tested my cables, and at least to my knowledge the system is functional and so I believe I did not mess anything up too badly.

 

 

My current understanding is this is fine, since "there is only one 12 V rail" and so which cable drawing from a particular PSU 12 V pin is not important. So my first two questions are:

 

1. If the above statement is true, is there a particular reason why stock cables are criss-crossed by default? Are there really no downsides to re-wiring the pinouts of a PSU, for the sake of simplicity, let's say within a cable (i.e., no re-wiring between a 24-pin and a 8-pin PCIe, for example)

 

This then led on to the next question, how about for multi-rail PSUs? I understand that some multi-rail PSUs are not actually multi-rail etc etc, but nonetheless....

 

2. In the case of multi-rail PSUs, are individual cable sets (i.e. an 8-pin EPS, 8 pin PCIe, 24-pin ATX, etc) on one rail at a time, and therefore if you were to re-wire within a cable, it also wouldn't matter?

 

3. If not, what can be done to avoid doing bad things to the system

[Radium_Angel]

21 minutes ago, For Science! said:

is there a particular reason why stock cables are criss-crossed by default?

I do not know the reason, but given it's a power connection, I assume there is a solid reason, and playing with power can be...dangerous.

 

[For Science!]

1 minute ago, Radium_Angel said:

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I can understand that for some cables that are split between the 12V and a sense wire, it would make sense to keep those to paired together going to the intentional output pin, but for these non-split 12 V cables....I'm not sure, so perhaps an expert can shed some light.

[Radium_Angel]

9 minutes ago, For Science! said:

so perhaps an expert can shed some light.

Have you contacted cablemod.com? They might have the answers.

[BrinkGG]

 

 

From my understanding for single rail PSUs, as long as your rewiring does not change the VOLTAGES of the pinout (moving a 12v line to a 3v pin, etc), it does not make a noticeable difference. 

 

.

[For Science!]

2 minutes ago, Radium_Angel said:

Have you contacted cablemod.com? They might have the answers.

Can try to summon them here too @CableMod, hopefully they're also happy to give insight to those making cables themselves 

[For Science!]

7 minutes ago, BrinkGG said:

From my understanding for single rail PSUs, .

Any idea how about for multi-rail?

[BrinkGG]

5 minutes ago, For Science! said:

Any idea how about for multi-rail?

Not gonna lie, any power supply worth it's weight is usually single rail. I've not been able to find new single rail PSUs for a long time, and their designs are fairly dated since single rail is so efficient now.

That being said, usually the rails are split so that each connector only has one "rail" of voltage, an example being a PCIe power connector's 12v lines all being on the same 12v rail, EPS all being on one rail and so on. So as long as you don't miswire a sense wire to 12v or visa versa, you should be fine. 

 

Check out this video for more info: https://www.youtube.com/watch?v=dQw4w9WgXcQ

 

[For Science!]

7 minutes ago, BrinkGG said:

Check out this video for more info: https://www.youtube.com/watch?v=dQw4w9WgXcQ

 

Not gonna lie, you got me good there.

[BrinkGG]

52 minutes ago, For Science! said:

Not gonna lie, you got me good there.

April fools is in full swing here   

[Guest]

3 hours ago, For Science! said:

I can understand that for some cables that are split between the 12V and a sense wire, it would make sense to keep those to paired together going to the intentional output pin, but for these non-split 12 V cables....I'm not sure, so perhaps an expert can shed some light.

It's just the manufacturing process.  Nothing more.  They're not putting the pins in one at a time.  The worker knows what pins are +12V and what pins are ground.  They put the connectors on accordingly.  If some of the wires get twisted in the process, it's no big deal as long as +12V and ground doesn't get switched.

 

The way your wires were crossed may very well be completely different than the next guy's.

 

[For Science!]

2 hours ago, jonnyGURU said:

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That's great to know. Could you give any insight as to how rails are setup "typically" for PSUs? Would doing the re-wiring on a multi-PSU require any more attention that with a single rail PSU? (This is still assuming re-wiring is only within a cable).

[Guest]

15 minutes ago, For Science! said:

That's great to know. Could you give any insight as to how rails are setup "typically" for PSUs? Would doing the re-wiring on a multi-PSU require any more attention that with a single rail PSU? (This is still assuming re-wiring is only within a cable).

A PSU with multiple +12V rails would have those rails split up per connector.  So it doesn't matter if you're doing a fully modular PSU since you're not re-wiring the actual connectors on the PSU.