Amps vs. rails?

[Ninja Please!]

okay is a 4 12v rail that has 18a on each rail a good enough psu to power 2 gtx 285's? It is 700w nvidia sli ready, but it is a lesser known name brand so I am worried. I'm not proud but it is a "KINGWIN Mach 1 ABT-700MA1S 700W ATX / BTX SLI Certified CrossFire Ready Modular Power Supply". The sale price suckered me in. $119 (USD). I have only read one review with a person using this psu for 2 gtx 280's but one review is not enough to convince me this psu is solid.

btw- will also need to power 2 ocz vertex's (only ordered 1 but will eventually get another for raid) 500gb wd hd, 1 cd burner, 1 dvd burner. the rest is in my specs.

my current psu is 600w nzxt. 2 12v rails @21, 22amps. I was told that amps mean more than 12v rails and that higher amps will help stablize an overclock. Is there any truth to that?

Any advice/suggestions will be greatly appreciated.

 

[Sasahara]

Hmm, seems to be a bit of confusion here.

For reference, you may well know this:
Amp is a unit of Electric current.
Wattage/Voltage = Amps

It's pretty much definate that 4 12v rail is just 1 rail divided into 4. Very few PSUs have more than one real rail.

The maxium current a GTX285 can take is 18.75A due to the power connections it uses and Nivida states 204 W (17A)

So just for both cards you need a +12v rating of 34A (408w)

Then the rest of the +12v requirment, another 10A on +12V (some overhead included here)

So you need to find if the combined +12v rating is at least 44A (528w)

The rest of the system should be under 100w.


If you can finds out it's +12v A rating you can see if it would work, but you would be pushing it close to the limit.

I'd always spec a PSU to go up to 80% of it's max load, as they do age.

Also you would need 4 PCI-e power connectors, it's probably not a good idea to use too many molex adapters.

 

[Sasahara]

Found this.

http://www.hardwaresecrets.com/article/624/1

It does seem this psu would cope with 2 GTX285 and the rest of your system.

Having a max of 58A on the +12v is well in your required level.
(on a practical level 44-6A is pretty much it's peak as you need to power the rest of the system)

And I see it does have all the pci-e connectors.

The down side is it's not a premium unit, so it has lower efficiency.
May not last as long as some better brands (but it could).

 

[Ninja Please!]

Thanks very much for the advice, you helped to clear things up for me.