single vs dual rails PSUs...

[fkdup74]

I been reading about dual vs single rail PSUs
some people theorize that a single rail would be better than a dual rail = the same amperage
i.e. (1) 30A rail vs (2) 15A rails, something about wasted power, blah blah blah
or getting into a situation where one rail is limited while the other has idle power

comments? thoughts? spam?

[volskid2002]

i belive that a dual rail psu is geared toward sli mode so that each rail will correspond to a videocard

[lynx]

A PSU which has to supply a single 30A rail is under far more stress than one which has to supply 2x15A rails.

In any case, I think you will find that if it was actually supplying 30A on the 12V rail in addition to the other supplies it would almost certinaly be exceeding its design rating. In comparison, supplying close to 15A on a maximum 15A rail is not likely to exceed the rating, as long as the other rail is reasonably unloaded.

In addition, the rail supplying the motherboard will probably have a fairly constant load, the other rail which is presumably supplying power to disk drives, optical drives, etc will almost certainly have transient power fluctuations. These are far easier to manage on a relatively unloaded circuit. The same transients on a heavily loaded single rail can cause sufficient voltage drop to induce system failures.

I suspect that the people who have theorised about wasted power, idle rails etc, probably have little knowledge of the reasons behind the design.

[clocker]

I suspect that the people who have theorised about wasted power, idle rails etc, probably have little knowledge of the reasons behind the design.

i belive that a dual rail psu is geared toward sli mode so that each rail will correspond to a videocard