Are multiple +12V rails considered bad for a PSU?

Here's the power supply:

http://www.newegg.com/Product/Product.aspx?Item=N8...

I'm gonna be running a GTX 560 Ti on this, and I just want to make sure that the multiple 12V rails aren't a problem.

Update:

What about 3 rails? The specs of this power supply says there are 2 12V Rails at 22 Amps, and a 3rd 12V rail at 25 Amps.

3 Answers

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  • Jim
    Lv 7
    9 years ago
    Favorite Answer

    >No, two rails are better than one. The higher quality power supplies have two rails, so that all the pressure from the electricity is not going to a single rail. Single rail supplies frequently burn out faster.

    Just like water, think of current as the pressure. If you have twice the volume of water going through a pipe, you double the pressure on the water. In this case, each rail acts to split the electrical current up so that there isn't so much pressure on just one, thus easing the electrical balance.

  • Anonymous
    9 years ago

    That's a very complicated question. If all power supplies were labeled properly, the answer would be MAYBE. In general...a SINGLE +12V voltage rail power supply will work for all systems (if the specs. are otherwise OK). A multiple +12V voltage rail power supply might be OK, if the video card(s) you are using are NOT high-end. The problem is the supposed current limitation. High end video cards can draw more current than some (split) voltage rails can provide. If you are building a gaming system at all or aiming for any kind of higher end build, get a power supply with a SINGLE +12V voltage rail.

    Now here's why the question is complicated. There are very few power supplies that actually have multiple +12V voltage rails. For every 100 power supplies that claim to have multiple +12V voltage rails, you might find ONE of them actually does. For the most part, multiple +12V voltage rails are just marketing gimmick. Internally, you'll find that all the supposed rails are tied into one. Sometimes they are split with some kind of current limiter (off of one +12V rail, several are created). Sometimes there's not even an effort to try to split the one rail...

    If for no other reason than "it's better to trust a manufacturer who doesn't lie to you", it would always be better to buy a power supply that claims to have a single +12V voltage rail. Because 99.99% of them do, even though a good percentage of them claim otherwise...

    As for your system specifically, I'd suggest you switch to this:

    http://www.newegg.com/Product/Product.aspx?Item=N8...

    Not only is it better quality than the one you linked to (for the same price), but the manufacturer states (correctly) that it only has one +12V voltage rail.

  • 9 years ago
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