Combine rails?

[orphan01]

have two 7900gt's that require 28A. I've looked EVERYWHERE and i cannot find a psu with multiple 12V rails that can give this many amperes. Is it the amps PER rail that are important or the combined total of amps of all rails? Also, how do i know whether or not a psu allows you to combine rails? I hear this is possible.

I've been looking at this psu and i think its great but i dunno if i can combine the 12v rails or not for the added amps.
http://www.newegg.com/Product/Produ...N82E16817104015


AMD athlon 2.2ghz 64bit 4200+
Vapochill Micro
eVGA 7900gt x2 sli @ 550mhz
Antec Truecontrol 2.0 550w psu
Asus A8n SLI premium
74gb WD raptor
300gb Maxtor Diamond
Corsair x2 1gb XMS ddr400
Air cooled: x3 80mm, x2 120mm

 

[Apokalipse]

the AGP/PCI-E slot provides most of the power it needs. the molex plug will provide the rest

 

[Nitestick]

part of the power will com from 12v2 (second rail) via the 6 pin pci-e connector. a lot of the power will come from 12v1 (first rail which powers motherboard) via the ATX connector and any additional power connectors on the motherboard.

 

[PZEROFGH]

[color=blue-green]The link doesn't work, but you want to add the 2,3,or 4 rails up for the total[/color]