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From what I've been reading, the newer PSU's with dual-rails should be set so that one goes to the mobos/cpu only while the other goes to the video cards, etc... The question is, how does this typically get split when you are physically connecting them to the back of these PSU's. I just bought a Antec Earthwatts 500Watts which is replacing an old 4 year-old single-rail PSU...

The old PSU (an Ultra XConnect) has one main 20-pin ATX power cable to the mobos and the rest of the cables (HD, DVD, Videos Cards) I just plug into any of the rest of the empty outputs...

One +12V rail will be dedicated to the ATX 24-pin snake. The other rail powers all of the remaining +12V sources. The rail split has already been done for you.

Captain Ned wrote:

One +12V rail will be dedicated to the ATX 24-pin snake. The other rail powers all of the remaining +12V sources. The rail split has already been done for you.

Thanks for the info Captain . Does that also mean my old Ultra PSU was using was only utilizing one 12V source even though I can it connecting to all these different outputs from the back of the PSU box?

Also a lot of these multi-12V rail PSUs actually have just a single 12V source anyway. So as long as their combined output is enough you are ok.

Link

NeRve wrote:

Thanks for the info Captain . Does that also mean my old Ultra PSU was using was only utilizing one 12V source even though I can it connecting to all these different outputs from the back of the PSU box?

The reviews I've found cite a single 34A +12V rail, so everything needing +12V used that.

Flying Fox wrote:

Also a lot of these multi-12V rail PSUs actually have just a single 12V source anyway. So as long as their combined output is enough you are ok.

Most of the multi-rail stuff is standards compliance. The rails are split so that if one goes down the devices connected to it go down as well, rather than sucking power from the remaining rails. ATX standards compliance requires this because the 12ga wires used in the PSU leads are rated for 20A maximum. The 60+A single-rail PSUs are capable of sending all 60A down a single 12ga +12V wire, which is triple the current it's rated to carry. Granted, a failure chain that results in a single +12V lead being asked to carry all +12V requirements is damn near impossible, but electrical codes don't have wiggle factors.