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12v rails: 1 vs. 2?

post #1 of 67
Thread Starter 
I need some education on something here.

What would life be like if I went with two 12v rails vs. 1?
post #2 of 67
ok on multiple rail PSUs you can only use what is available in that rail say you only need 4 amps but you have 26 you still use the full 26 and cant use it else where. that is why i prefer single rails. it provides amps to anything that needs it.
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post #3 of 67
2 12v rails usually means more amps. But there are power supplies out there that have a ridiculous amount of amps (60+) on a single rail. Supposedly single railed Power supply's are much more efficient than dual or quad railed. (Or even three rails. I have an antec with 3 rails.)
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post #4 of 67
my PSU has a single 60 amp rail. its quite nice dont have to track down the rail for my videocards or anytihing
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post #5 of 67
Most of the times it's used as a marketing gimmick. Who even needs 8 12v rails? PC Power and Cooling is known to make great single rail PSUs that are on par or better than the multiple rail PSUs that Galaxy, OCZ and all the others are trying to sell you.

As long as the cumulative amperage is high enough, there isn't a problem.
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post #6 of 67
Sorry all, I just got the smackdown from JG for giving similar advice. I'll link the thread in a minute.

That said, I, PERSONALLY advocate the single-rail design. Look at all the top record-holders.
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post #7 of 67
Thread Starter 
Quote:
Originally Posted by Retrospekt View Post
2 12v rails usually means more amps. But there are power supplies out there that have a ridiculous amount of amps (60+) on a single rail. Supposedly single railed Power supply's are much more efficient than dual or quad railed. (Or even three rails. I have an antec with 3 rails.)
Much more efficient? That's a weird thing to hear considering this page at NewEgg. It's all of their 80+ Certified PSU's, and only a couple out of the 72 have a single rail.
post #8 of 67
As far as I know:

Back when multi-rail PSUs became the thing to have (maybe 4 years ago?), I believe the official ATX spec for PSUs didn't allow the 12V rail to have more than 20A. Because of that, they just loaded more 12V lines to provide power to different components (vid card1, vidcard2, mobo, etc.).

Now that there are PSUs that have plenty of power on one accurate rail that will give power wherever it's needed, single rail, high power PSUs are preferable.

I have a 3 rail PSU from a year ago. It is quality, it works just fine, but its architecture is not what I'd prefer.
post #9 of 67
Thread Starter 
I read something somewhere at NewEgg that a single rail is much easier somehow, but I can't remember anything else.
post #10 of 67
Actually, multi-rail is more efficient. electrical loss in watts = Resistance * Amperage squared (not sure about the formulaI'll have to check) if I remember right, so have more amperage on one line means that you loose more of it in the end. This is why companies who distribute electricity use high voltage lines with the least amperage. But in a non-critical environment like a computer, is it really necessary?
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