Should i run single rail or multiple rails mode? whats the difference?

[ProRules]

Hey fellas.

I have HX850 Platinum powersupply.

I took a look in the specs, it has either single rail mode with 70.8A - 850W.

Or  7 rails, each having 40A and 850W across them.

Which mode should i run? is there a benefit for each mode?

I will be running 7700K on 5.2Ghz 1.39Vcore (in the future will be upgraded to Ice lakes 8 core and ofc overclocked - custom WC)

Ram DDR4 16GB 3600Mhz on CL15 1.4V

And a GTX 1080Ti with an overclock.

 

I mean, i doubt each 8 pin connector will have more ampers than 40 anyways.

For example a GPU is double 8 pins, so each up to 40 amps = 80 amps total? how does it work, single rail having 70.8 ampers, yet 7 rails support each 40 amps?

[Sakkura]

Having multiple 12V rails makes it a little easier for an individual rail to be overloaded and cause the power supply to shut down. With 7 rails at 40A each, it's basically impossible for an overload shutdown (OCP) to happen from a legitimate load, but it could conceivably happen if there's a partial short-circuit in a connector. Then having the lower 40A limit for the rail with that connector increases the chance that whatever's connected won't get burnt to a crisp before the unit shuts down.

 

The ratings don't mean each rail can supply 40A simultaneously, just that the shutoff point (OCP) for each rail is around 40A (probably slightly higher, eg. 44A).

 

TL;DR multiple rail mode theoretically increases safety slightly.

[ProRules]

6 minutes ago, Sakkura said:

Having multiple 12V rails makes it a little easier for an individual rail to be overloaded and cause the power supply to shut down. With 7 rails at 40A each, it's basically impossible for an overload shutdown (OCP) to happen from a legitimate load, but it could conceivably happen if there's a partial short-circuit in a connector. Then having the lower 40A limit for the rail with that connector increases the chance that whatever's connected won't get burnt to a crisp before the unit shuts down.

 

The ratings don't mean each rail can supply 40A simultaneously, just that the shutoff point (OCP) for each rail is around 40A (probably slightly higher, eg. 44A).

 

TL;DR multiple rail mode theoretically increases safety slightly.

But it won't restrict me in any way right? even with all the overclocking?

[Sakkura]

3 minutes ago, ProRules said:

But it won't restrict me in any way right? even with all the overclocking?

Nope, it shouldn't. Corsair would have had to put like all the PCIe power connectors and the CPU power connector on one rail for you to possibly exceed 40A (480W) on one of the rails, and they're not that stupid.

[ProRules]

1 minute ago, Sakkura said:

Nope, it shouldn't. Corsair would have had to put like all the PCIe power connectors and the CPU power connector on one rail for you to possibly exceed 40A (480W) on one of the rails, and they're not that stupid.

Okay thank you!

Appericiate you taking the time answering me.

If you don't mind, i would love an explantion on how a failure can happen because of a connector.

Like, if there is something wrong with it, with 40A limit of 480W it won't get overpowered in a wrong way as much as a full 850W before PSU shutdown?

If such thing occurs, can it damage other hardware on the same rail? or just fry that specific connector?

Cheers

[Sakkura]

A low-quality or damaged power connector could have a partial short-circuit so it draws a lot of power and starts to melt or burn. That can damage the connected device, without the current having exceeded the 70.8A that would shut down the power supply in single-rail mode. With the lower 40A limit, it's more likely that the power supply would shut down.

 

I don't think it would affect other components powered from the same rail.

[ProRules]

3 minutes ago, Sakkura said:

A low-quality or damaged power connector could have a partial short-circuit so it draws a lot of power and starts to melt or burn. That can damage the connected device, without the current having exceeded the 70.8A that would shut down the power supply in single-rail mode. With the lower 40A limit, it's more likely that the power supply would shut down.

 

I don't think it would affect other components powered from the same rail.

Thanks man!

I'm done here ^^