Multiple 12v rails need help

[akashic]

I've been looking at a few PSUs i've been looking at this one for a I5-760 + HD5770 build (shouldn't be a problem as far as i can tell looking at wattage): http://www.newegg.com/Product/Product.aspx?Item=N82E16817341016

As far as i can see on the lists there is stickied(always on top thingy) on this section of the forum, that PSU should deliver 36AMP which should work with the HD 5770(even though the recomende is set to 37A@12v it saies that 30A will be just fine), now my question is, if there is multiple 12v rails does it always add up, like in this case its got 18A@12v1 and 18@12v2 (total of 36A) is that just something that is "unique" for this PSU or is that how it works regardless of how many 12v rails there is?

 

[rolli59]

It usually does not add up like that, very common that the total combined is around 75% of them added up. That is plenty for a HD5770. A good quality 450 watt unit would be enough.

 

[akashic]

1. you don't add amps up to get a total. its from the watts on the 12v rail
2. that PSU actually has one 12v that has has been split, see the link
http://www.jonnyguru.com/forums/showthread.php?t=3990
3. the PSU you picked out is a solid one but this one is better and cheaper out the door
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139004&Tpk=corsair%20550w

In my country the OCZ is roughly 5$ cheaper then the corsair if i use two different sites for a price i would have prefered the corsair vx550 but it is (on the site i'm currently looking at) the Corsair is apx. 24$ more expensive (shipping ~12$ on either site) and seeing that the corsair is the only thing there is cheapest on the others site it doesn't make sense taking things from two different places (the prices is calculated using currency enchange rate) But thanks for the advice

 

[rolli59]

^+1

 

[akashic]

Best answer selected by Akashic.