Antec CP-850 - Amps too low for overclocking?

[Celrond]

I just recently bought the Antec CP-850 Powersupply based off the excellent reviews I have read. Now, after doing a little research on a new vidcard, I am having second thoughts about this PSU: When I was looking for a new videocard on newegg, I came across the EVGA 560. The specs for this card state that a minimum 12V current rating of 30A is required to operate this vidcard. The CP-850 features "only" 22A on the 12V line.

Bottomline, have I made a mistake buying this PSU? Should I have paid more attention to Amperage on the respective lines, especially on the 12V? Have I have limited my choices as to which vidcard I can buy and will I ever be able to overclock a CPU with this PSU?

[powerarmour]

I'm pretty sure you will be fine!, it might be ~22A per +12v rail, but you've got quad +12v rails (@ 768W)

Enough for a pair of GTX 560's with ease IMO.

[Celrond]

So even if they have separate rails? Does it make any difference if they are on separate rails? I understand I have the wattage and that part makes sense to me. What I don't quite grasp however, are the separate rails and how the amps are "distributed" and if it matters whether they are all on a single rail or not. Here's how I understand it so far: If I had 4 x 12v lines, all on a single rail, then the total amps combines amount to 68 amps. In my case however, the lines are "separate" (Is that what Quad Rail means??).

[wonkanoby]

Is that what Quad Rail means??).

yep

each can give up to 22amp

if they designed it right no problem

if one wants 30 amps your out of luck

myself i prefer single rail were it can get to all the amps

[Celrond]

To conclude: I have 4 PCI-E lines on two separate rails, which gives me 50 Amps per rail. Since the 560's requirements are 30 Amps, I have more than enough as most PSU's run their 12V lines off a single rail. Even if the 4 PCI-E lines ran on a single rail, I'd still have enough since nVidia is making a very conservative assumption that most use a single rail 12V for all components.

In a nutshell, I have 84A.

[powerarmour]

Ah, I didn't realise it was a dual rail, then in that case you obviously have plenty enough power...

[wonkanoby]

you can never have 84a

as to get that you would have to build a pc can exactley pull the max amps of all 4 rails

and in real life that never happens

as one or 2 will be lighter than max loaded evan if one can be near max

[Celrond]

I simplified. I'm not saying that I would ever be pulling 84A off a single line or even all of them combined, the max I can pull is 25A (or 22A) per rail. What I am saying is that I have 84A distributed over 4 rails. OCP limits the max I can pull to 2x25A & 2x22A for each rail, respectively.

EDIT: When nVidia states one needs 30A on the 12V line, that's the same as when they say you need a 500W PSU. The card will never actually pull that much juice. When they say you need 30A on the 12V line, they assume that most people operate a PSU with one single 12v run supplying juice to ALL the components (CPU, drives, videocard etc). In reality the Card will pull maybe 15A or 170W.

Edit II: I stand corrected, the combined 12v rating is 64A..!