Paging Power Supply Guru's

[OVERKILL]

All relevent information is appreciated.


Thanks ahead

 

[Bobthelost]

Minimal pros, it means you can't put massive amounts of power down each wire (causing overheating) and it means that you can use cheaper compoenents.

Cons include complexity, crap assignment of power, load balancing and general arsing about.

If everything else were equal i'd want the single rail PSU over a double or quad.

 

[GalvanizedYankee]

OVERKILL, read in total please http://www.silentpcreview.com/article28-page1.html
The stuff of real interest starts on page 3.

...Galvanized

 

[acegazda]

dual rails were instated by intel to try to solve the problem of failing rails. For instance: if one 20amp 12v rail out of 2 fails, it will cause less damage than if one 40amp 12v rail fails. Or something like that. Some people say that the dual rails provide cleaner power, those people are crazy. Generally, for a single part that will draw a ton of power such as a peltier cooling system or a heavily oced fx62, perhaps a single rail is better, becasue one rail of the dual rails is dedicated to the cpu/mobo and one for the other stuff. This one rail for the cpu could theoretically be maxed out and it would fry. Not really possible with a single strong rail. Fortunatly, today's cpus will not even get close to maxing out a rail capable of 18amps. Hope this helped!

 

[JEDIYoda]

Originally posted by: acegazda
dual rails were instated by intel to try to solve the problem of failing rails. For instance: if one 20amp 12v rail out of 2 fails, it will cause less damage than if one 40amp 12v rail fails. Or something like that. Some people say that the dual rails provide cleaner power, those people are crazy. Generally, for a single part that will draw a ton of power such as a peltier cooling system or a heavily oced fx62, perhaps a single rail is better, becasue one rail of the dual rails is dedicated to the cpu/mobo and one for the other stuff. This one rail for the cpu could theoretically be maxed out and it would fry. Not really possible with a single strong rail. Fortunatly, today's cpus will not even get close to maxing out a rail capable of 18amps. Hope this helped!

Intel has since backed from there stance concerning dual rails..

 

[Howard]

Originally posted by: acegazda
dual rails were instated by intel to try to solve the problem of failing rails. For instance: if one 20amp 12v rail out of 2 fails, it will cause less damage than if one 40amp 12v rail fails.

First time I've heard that explanation.

 

[jonnyGURU]

Also see: http://forums.anandtech.com/messageview.aspx?catid=27&threadid=1815673

Post three and four.

And JY is correct. Intel has increased their "requirement" for maximum output per rail, but have not yet published this in a more up to date ATX12V specification.

 

[alimoalem]

Originally posted by: jonnyGURU
Also see: http://forums.anandtech.com/messageview.aspx?catid=27&threadid=1815673

Post three and four.

And JY is correct. Intel has increased their "requirement" for maximum output per rail, but have not yet published this in a more up to date ATX12V specification.

?? johnny's still here!

OP, i don't have anything to contribute (sadly) but just wnated to show my love

 

[acegazda]

Originally posted by: Howard

Originally posted by: acegazda
dual rails were instated by intel to try to solve the problem of failing rails. For instance: if one 20amp 12v rail out of 2 fails, it will cause less damage than if one 40amp 12v rail fails.

First time I've heard that explanation.

I did some research. Welcome back JG

 

[OVERKILL]

I read the links guys, I appreciate it.

And Jonny, thank you for posting in this thread.

 

[Navid]

Let's have a competition.
Let's see who else can make a thread that would make jG post in it!

 

[Mark R]

Originally posted by: Howard

Originally posted by: acegazda
dual rails were instated by intel to try to solve the problem of failing rails. For instance: if one 20amp 12v rail out of 2 fails, it will cause less damage than if one 40amp 12v rail fails.

First time I've heard that explanation.

That is pretty much the key reason.

The point being that if you have 2 or 3 seperate 12V rails - they can be current limited to 20 A (or near enough) each.

Let's say that the main regulator on the mobo failed and started taking excessive current. That fault current could easily be 50 A. If you've got 12 V lines, which are limited to 20 A, the protection circuits in the PSU will immediatly shut off the PSU.

If you had a single rail which was limited to 60 A - then this same fault wouldn't not be detected by the protection system. Instead you would continue with 600 W of heat being produced in the mobo (that's a serious amount of power, and will almost certainly result in the mobo catching fire).

Essentially, if you've got low current limits on your PSU - then faults will tend to fall into 2 categories: 1) low-power continuous faults which cause minor damage, or 2) high-power faults which immediatly activate protection systems.

If you make individual rails more powerful, you necessarily reduce the sensitivity of protection systems. You now add a 3rd category of fault: 3) medium-high powere continuous faults with risk of severe overheating or fire.

It's the same reason why in your home, you have lots of 16A or 20 A circuits. You don't run everything off the 200 A mains supply directly. It's a lot easier to deal with a fault if the circuit is protected by a 16 A breaker. (E.g. if a lightbulb is shorted out, but is protected by a 6A breaker - the breaker will simply trip out, and you would be unlikely to notice anything). If that 6A breaker was removed, and the circuit was connected directly to a 200 A service - the light fitting and wiring in the walls would probably burst into flames within a couple of seconds.

As it turns out, with modern CPUs and graphics cards requiring ever increasing amounts of power - the current limits on each individual rail have become a problem - leading to wasted capacity, and difficulty supplying enough power to key components.