Why is there a Y-splitter on the PSU side of MOBO power?

[Jumper]

Why wouldn't it be a single cable?

Is there any situation where you shouldn't connect the other one?

 

The other side is just a regular 24-pin

[Bob__]

3 minutes ago, Jumper said:

Why wouldn't it be a single cable?

Is there any situation where you shouldn't connect the other one?

 

The other side is just a regular 24-pin

maybe to give the internals some breathing room. to make sure u don't screw up the orientation. Thats all I can think of

[manikyath]

iirc it's a board layout thing, the split mostly existing to route things in between.

[seon123]

The PSU side has extra pins for Vsense wires. The PSU uses them to measure the voltage on the motherboard side, so it can provide a more stable voltage. 24 pins are already difficult to plug in, so the 28 pin connector is split into 18+10 pins, so it won't require quite as much force to plug in. 

[OhYou_]

it is for isolation. 

internally, power supplies have all of the beefy power outputs physically isolated from the actual control portion. 
 

[Agall]

16 minutes ago, Jumper said:

Why wouldn't it be a single cable?

Is there any situation where you shouldn't connect the other one?

 

The other side is just a regular 24-pin

Its just how some power supplies are designed. There's no standard for PSU side connectors so companies will vary how they layout especially the physical connectors on the 24 pin. Some are 1:1 'extension' type, some use this 18+10, some do 20+4, 24+4, it really depends on what the manufacturer wants.

 

I emailed Seasonic about this a couple weeks ago to ask about this specifically.

[Spotty]

8 minutes ago, seon123 said:

The PSU side has extra pins for Vsense wires. The PSU uses them to measure the voltage on the motherboard side, so it can provide a more stable voltage. 24 pins are already difficult to plug in, so the 28 pin connector is split into 18+10 pins, so it won't require quite as much force to plug in. 

^ This is the correct answer.

 

The connectors used are Molex Mini-Fit Jr. Molex does not manufacturer a 28 pin connector housing for the Mini-Fit Jr. series. This means if power supply manufacturers want 28 pins (for the additional voltage sense wires) they need to use two separate connectors, hence 18+10.

 

29 minutes ago, Jumper said:

Is there any situation where you shouldn't connect the other one?

You always need both connectors plugged in.

 

23 minutes ago, OhYou_ said:

it is for isolation. 

internally, power supplies have all of the beefy power outputs physically isolated from the actual control portion. 

I don't even know what this is supposed to mean.

[OhYou_]

14 minutes ago, Spotty said:

I don't even know what this is supposed to mean.

well what i assumed was the p_on, p_ok, grounds, and 5vsb would be on the 10-pin and the other power rails all on the other ones because that makes sense. 

 

i looked it up, it actually just makes little sense. Maybe they just like more wires and outputs for further standart compatibility or ass-covering idk

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