Single-Rail vs. Multi-Rail vs. modular PSUs

[Gig-O-Ram]

I need to finish it, but I started reading an article in "CPU" magazine that profiles and reviews PSUs. The article covers all the advantages and disadvantages of various units, and has input from the head guys from Enermax, OCZ and PCP&C.

One thing about it that has me wondering which way to go when I build my next rig is the fact that both single and multi-rail units seem to have some fairly concerning drawbacks - mainly that multi-rail units apparently have a tendency to not evenly distribute power, and that single rail units, while giving the system everything it needs, can cause current rush in the event the unit fails.

The guy from PCP&C (Doug Dodson) states that modular units can cause voltage drops and increase resistance, limiting overall power delivery because the pins aren't rated for more than 5 amps. Ryan Peterson of OCZ counters that modular units can help with airflow to the case.

Now, while I've never used a multi-rail PSU, I have never had any issues with single rail units. I've used both modular and non-modular types, with no problems, except the my current PSU seems to have slight power dips in the rails. My wife's rig has my old modular OCZ Modstream 450W, and has no issues that I've seen.

Any thoughts on this?

[One4yu2c]

Originally Posted by Gig-O-Ram

Any thoughts on this?

In short, it doesn't really matter. The bigwigs can argue theory all day long, but both multi and single rail power supplies from reliable and reputable PSU manufactures have shown their worth both in online reviews (including the ones that do in depth testing), and real-world settings.

EDIT: There's a 5-page discussion we recently had on this very topic, which can be read HERE.

[gvblake22]

There is a fairly lengthy discussion on this topic here...
I think Paul is on the right track. In the end, it really doesn't matter, as long as there are no components on a single +12V rail that will require more Amps than what that particular rail can output. For that reason, I kindof like the idea of going back to the single large +12V rail like Silverstone is doing on their Olympia and Decathlon units and what PC Power & Cooling has been doing. But for the majority of systems, any decent multi-rail unit should perform just as well.
The modular argument about pins adding resistance and being rated for 5A is pretty dumb because there are pins on the cables wherever there is a connector for a device, so it seems like a moot point.

[Gig-O-Ram]

Originally Posted by gvblake22

The modular argument about pins adding resistance and being rated for 5A is pretty dumb because there are pins on the cables wherever there is a connector for a device, so it seems like a moot point.

You know, I didn't even think of that when I read that guy's comments. Good point. I suppose if they figure a way to hardwire components to the PSU, then maybe his point would be valid, but until then...

[Computer-Ed]

On the sites that do the INDEPTH testing of the PSUs look at the modular PSUs they tested. The Modular designed never seemed to make any difference in the test results. Now that is not to say the potential for a difference is not there, but the testing would seem to indicate that if there is a difference it is minor.