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12V Rail

Last response: in Graphics & Displays
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December 8, 2010 7:39:29 PM

Was just watching a review on youtube on the GTX570 and on the side of the box it says that minimum power supply 550w with a minimum 12v current rating of 38A. Now sorry if this is a bit of a noob question but how would you know if your MB has that requirement,not the 12v rail but the 38A minimum.

More about : 12v rail

a c 130 U Graphics card
a b ) Power supply
December 8, 2010 7:46:15 PM

It's your power supply not the motherboard that you'll be looking at. There'll be a chart on it that will say +12vx @ 42a, or something. x is a number (there is +12v1, +12v2, etc).
a b U Graphics card
a c 243 ) Power supply
December 8, 2010 7:46:52 PM

Not an MB rating that you're looking for.
Read the label on your psu, find out how many watts are available to the 12v.
Watts divided by volts equals amps.
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December 8, 2010 7:54:29 PM

Ok,thanks very much fellas,much appriciated.
December 8, 2010 8:06:50 PM

The motherboard allows for any aperage the power supply can push. Your real concern is that the power supply has 38A or more. Ignore the motherboard pay attention to the power supply details.

So lets say a power supply has...

16A-1 16A-2 16A-3 16A-4
The total 12V amperage for that would be 64A which is more than enough for that video card.
Some power supplies like the one in my computer only have 1 12V rail. The example I gave above has 4 rails. Mine has only one but that one rail provides 49A. Which is also more than enough for that video card. The number of 12V rails a power supply has doesn't matter. I can't remember the details but I believe it's safer for a PC to have several rails as apposed to 1 big one.

This is a good example of a power supply with multiple rails:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Click on details and look at the "Output".
+12V1@25A, +12V2@25A, +12V3@25A, +12V4@25A
If you stare at it long enough you can figure out that the total 12V amperage is 100A, which is a hell of a lot more than most people need.
BUT...
on the other hand people like to add more than 1 video card these days.
to of those cards would require 76A and this power supply would not be enough for 3 of those babies! But that's why they make even bigger power supplies. The biggest one I saw on newegg right now has 1500Watts and 175A. That much amperage is enough for 4 of those video cards!!
(Personally I only run 1 video card so 49A is plenty for me.)
December 8, 2010 8:11:03 PM

Ok i have 1000w 4 +12v rails each with 20A so thats more than enough then.....happy days. Thanks Dark_lord69

Begining to think i should have put this in CPU&Components.The thread did start off with me mentioning the GTX570 tho lol.Sorry.
a b U Graphics card
a c 243 ) Power supply
December 8, 2010 8:15:42 PM

dark_lord69 said:


This is a good example of a power supply with multiple rails:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Click on details and look at the "Output".
+12V1@25A, +12V2@25A, +12V3@25A, +12V4@25A
If you stare at it long enough you can figure out that the total 12V amperage is 100A, which is a hell of a lot more than most people need.

Some people might, those who know how to read the label will see the line ( a little further down ) that states the total 12v output to be 62 amps.

Oh, and you don't need to double the amperage reccomendation when doubling up on the cards.
December 8, 2010 8:21:09 PM

delluser1 said:


Oh, and you don't need to double the amperage reccomendation when doubling up on the cards.

Why is that,as the second card should require the same amount of power,or does it not work that way.
a b U Graphics card
a c 243 ) Power supply
December 8, 2010 8:24:28 PM

The power reccomendation is for the entire system, not the card alone.
December 8, 2010 8:33:56 PM

Ok,thanks for that delluser1,i was starting to think that my PSU was out dated already but its still got some life yet. Thanks again.
December 9, 2010 5:23:22 PM

Quote:
don't be uncertain about your power supply...!



By that,do you mean its ok?
December 9, 2010 7:16:48 PM

Oh ok,sorry,just wasnt sure what you meant,cheers for clearing that up.
!