Single or Multi Rail, does it even matter?

[House]

Ok Electrical stuff is all black magic to me, when people at work pull out a Single line diagram my brain locks up.

I have a 1200w Corsair unit for my New PC that will be getting a 4090 dropped into it,

The PSU has a switch on the back of it for Single or Multirail operation, my very basic understanding is that multi rail splits the power for the +12v into lumps, where as single lets you take all the power on all the connections.

Which should I select, does it even matter?

 

[EsaT]

On that size PSU I would use those current limiters for safety reasons:
If short circuit is in end of only one or two wires, resistance of wires themselves could keep current below threshold of protections.
And then you'll see insulation turn to smoke and glowy cables.

 

[no_1_dave]

Ok Electrical stuff is all black magic to me, when people at work pull out a Single line diagram my brain locks up.

I have a 1200w Corsair unit for my New PC that will be getting a 4090 dropped into it,

The PSU has a switch on the back of it for Single or Multirail operation, my very basic understanding is that multi rail splits the power for the +12v into lumps, where as single lets you take all the power on all the connections.

Which should I select, does it even matter?

Single rail, not much point in multi-rail for home use

 

[bjmnz]

I think the recommendation is that if you have the option to use multirail, you should.

There's an older article from Jon Gerow (former PSU reviewer JonnyGuru, now Corsair PSU R&D) here, also a video at the bottom of that page:
http://www.jongerow.com/multiple-12V-rails/index.html

Bit more on it here (PCWorld discussion with him):
https://www.youtube.com/watch?v=QJ_VV3UjEBY&t=286s

 

[JollyJamma]

My understanding was that single rail was better.