Power Supplies - Why would I want multiple 12V rails?

[DaveJ-UK]

Removed

 

[Cuchulain]

I think it's just a marketing gimmick, claiming draw balancing. A good quality, high amperage single rail PSU is just as good.

 

[Tealc]

Multiple rails was apparently part of the ATX specification back in 2003 where separate rails were supposed to power the 4pin ATX connector and everything else.

Most power is now provided on 12 V rails. The standard specifies that two independent 12 V rails (12 V2 for the 4 pin connector and 12 V1 for everything else) with independent overcurrent protection are needed to meet the power requirements safely (some very high power PSUs have more than two rails, recommendations for such large PSUs are not given by the standard).

I think this line means something too.

The absolute over current limit (240VA per rail) is no longer present, enabling 12V line to provide more than 20A per rail.

Maybe before this change in 2007 it was not possible, while remaining in the ATX spec, to have more than 20A on a single 12v rail. This would explain why a lot of PSU rails are 20A or less.

 

[DaveJ-UK]

Removed

 

[Divide by Zero]

Yeah, 70a max.

The whole arguement about rails is really a case of horses for courses. On paper it seems like a great idea to split your rails, but in reality, will anyone notice any difference?!

The only advise that is ever true about PSUs is make sure you buy a good one from a known make and do not scrimp money here. If your PSU blows, so can your entire kit.

 

[DaveJ-UK]

Removed