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Will multiple 12V rails on a psu affect power support?

If i get a psu with 4 +12V rails at 20A each and i get a graphics card, like the GTX 780, and it requires 42A on the +12V rail, will that psu be able to properly support and power the graphics card?
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More about multiple 12v rails psu affect power support
  1. What PSU are you looking at? There isn't much of a difference between Multi vs Single rail PSUs.
  2. P1nnacle said:
    What PSU are you looking at? There isn't much of a difference between Multi vs Single rail PSUs.


    the EVGA SuperNova Bronze 750W
  3. Yes, your combined 12V amperage is 61 Amps. More than enough for your card.
  4. P1nnacle said:
    Yes, your combined 12V amperage is 61 Amps. More than enough for your card.


    But i thought that if you only plug in, lets say, 2 PCI-E power cables to the graphics card, you would only have 40A going to it. Because isnt each only 20A? Im not good with power supplies and the rails are confusing me
  5. Best answer
    The load is distributed across the rails. Don't worry about the rails, the combined amperage will be enough.
  6. I'm a little shady on details but the original ATX spec called for multi 12v rails for safety reasons. It was around the time SLI was making a huge comeback when people were having load balancing issues. So single 12v started to come around.

    That was a long time ago. Any modern PSU won't have that problem. Antec had a good article on it. I will edit post if I can find it.
  7. I'm a little shady on details but the original ATX spec called for multi 12v rails for safety reasons. It was around the time SLI was making a huge comeback when people were having load balancing issues. So single 12v started to come around.

    That was a long time ago. Any modern PSU won't have that problem. Antec had a good article on it. I will edit post if I can find it.
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