PSU question

[westy87]

So I was cleaning my desk and stuff today and found my psu specs booklet and decided to take a look. I'm just curious, it has listed all the amps on each rail, and for the 12v rail there are actually 4 diff ones, 12v1 12v2 12v3 12v4. Each one saying it has 18amps. Now I remember from the cords that there are 2 seperate cords with 2 12v plugs on them with stickers saying 12v1 12v2 etc. basically I'm wondering how many amps my 12v rail can provide for when I need to consider upgrading my gfx card.

If I remember correctly the 8800gts uses about 22amps? So do i combine the 18's to get 36 for each cord (that has the 2 plugs per cord) or what?

[Victor]

most grahpics card will say combine 12V needs to have a minimum of xxx amps. Though that really dpeend on the quality and how the 12v is being distributed. If you got 4 lines of 12v, I would say you are fine with the 12v requirement.

Some lines are dedicated while others are shared, it's hard to say without knowing too much. Generally speaking, it's the combined 12v that's what the gfx maker states.

[PP Mguire]

Just use the PCI-E connectors that come outa your PSU and you should be fine. DOnt use the molex adapters cause it will get confusing since you have dedicated cords.

[westy87]

What I'm saying is how many combined amps do I have on my 12v? cause there r 4 raiils saying 18amps each im confused

[PP Mguire]

Then you multiply 4x18 :p hehe. Simple enough.

[westy87]

But surely I dont have 72 amps on the 12v?

[PP Mguire]

Not likely. Are you sure your manual is right? There should be a sticker on your PSU saying what is supposed to be what voltage. You usualy see 72amps on a KW PSU.

[Ranzear]

72a * 12v = 864w

My Tagan 1100w is rated 80 amps across the 12v linked rails, for 960 watts of the total.

Individual rails are just a way to keep one high power draw from sucking down the voltage for everything else, but one fat-enough rail does just fine and when sufficiently rated will have less voltage drop on the components that can't tolerate it.

[westy87]

OK so heres my PSU page

http://www.silverstonetek.com/products/p_contents.php?pno=st65zf&area=usa

And the specs

http://www.silverstonetek.com/products/p_spec.php?pno=st65zf&area=usa

It says I have 42amps total on the 12v (45 at peak) and it gives different amps for each 12v rail than in the booklet, very odd. But I think those specs clear things up for me

[sushrukh]

According to that Silverstone link , you PSU should have 55A total Amps combining all 4 rails.
55A comes from :- 13A+18A+16A+8A .The peak or load Amps can reach as high as 65amps bcoz the first & last rails can provide more 10amps total in peak.So, 18A+18A+16A+13A = 65A