Power supply for an ASUS GTX 680 DCU II top: Doubt with AMPERAJE

[Maegirom]

Good afternoon.
By a twist of fate, my ASUS GTX 670 DCU II top died, and through pccomponentes' RMA service, they offered me an ASUS GTX680 DCU II top-
The thing is, I now have doubts about whether my power supply can handle it.

It's a NOX PULSAR blue led modular 750W

I know I have enough watts, since it requires a 550W power supply, but I'm a bit lost with the amperage.
The 680 requires 38 amps on the 12V rail, and my power supply, like many others, has the 12V rail separated or divided into several: 12V1, 12V2, 12V3, and 12V4.
The specifications state:

• "Maximum combined watt 12V1+V2+V3+v4=660W"
• 12V1: 18A
• 12V2: 18A
• 12V3: 20A
• 12V4: 20A

I know that these divided amperages are NOT additive, meaning I do not have 76 amps (18+18+20+20) on the 12V rail, but I do not know the exact calculation to determine the real amperage of these 4 combined rails, and whether they can give me the required 38A
Does anyone know how this works?
Thanks and regards

[ferelxyx]

calmly it serves you well it is easy if it says Maximum combined watt 12V1+V2+V3+v4=660W
then you divide 660W/12V = 55 amps

regards

[Maegirom]

Thank you very much ferelxyx!