Yet another thread about power supplies

There has been much talk about power supplies and amps and rails in past few months here in the MG Hardware forum, and I have been a part of many of these discussions. It seems that in the past 6 months to maybe a year, the big-single-12v-rail is the way to go with high end power supplies, but only a year or two ago, multiple rails were all the rage. I recently skimmed a power supply review where the unit studied had a single rail of a massive 62a. The stated reason for this was that it "should provide better stability with a high end system because components that use the +12V rail are not split up". Now, it seems to me that having a 12v rail dedicated to each of the major components would be better than having a single rail. Having individual rails 'assigned' to the video card, CPU, hard drives/CD drives, and an extra rail for a 2nd video card or miscellaneous components makes more sense than having a single rail. In this example, a quad-rail PSU with 18a or 20a per rail seems that it would provide better stability and more even and 'smoother' distribution of power to the various components in the PC. It seems that a single rail would run the risk of being over-worked if too many components were hooked up to it.
Can someone shed some light on why the big-single-rail is now considered to be superior to the multi-railed PSU? When just a short time ago, the dual rail power supply was considered to be vastly superior, then came the triple and quad railed PSUs....

THANKS!

 

Well for one , when they made dual rail psu's the video cards didn't need as much amperage as they do now. As the amperage needs increased, the rail specs stagnated causing some rails to be overworked where others are only using say 50% of their power. Unfortunately the power not used can't be transferred to another rail thus making that power useless. One rail on the other hand has all the power there and not trapped on an under-utilized rail thereby enabling it to feed the power hungry components as needed. Hope that makes sense (If not the dog typed it )

 

Yeah, that makes total sense. But I'm thinking, on a multi-railed PSU that each rail is 'aimed' at a specific component (or group of components like optical drives). If a rail is under-utilized, no big deal. And the pull of high draw components would be separated from the other components and the draw would be confined to just it's own rail, not effecting the other rails. But if it was all on one rail, there's a chance it could actually draw juice away from other components. I see the benefits of both fat single railed PSUs and the multi-railed PSUs, but it seems to me that multiple rails is the way to go. But then again, I'm just voicing my opinion and I could be wrong :innocent

 

the only problem with that is say you have 4 x 20 amp rails and your video card requires 26 amps at full power (as in gaming)now the rail is only rated at 20 amps so the power supply is trying it's hardest to compensate for the overdraw on that rail.In the process the power supply overheats, shutting the pc down to save itself . A single rail say 60 amps on the 12v rail, feeds the card its full 26 amps and doesnt stress to do it, so unless your psu is right at the limit amp draw wise pulling from other components shouldnt be a problem.

 

Yeah, I get it. Kind of off topic, but how much does a modern video card draw? I don't mean like a top-of-the-line 9800GX2 or the nVidia 260/280, but something like a 9600GT or 8800GT.... the 9600GT doesn't draw more than 20a at full load does it?

 

not positive but hopefully someone here knows better I'm still a newb at this

 

Nahhhh.... I wouldn't say that