PSU reqirements for SlI rig

[therocker39]

I am preparing for my first build and I have a question about PSU for SLI. I want to make it clear I am not looking for PSU recommendations so much as technical info.

If a graphics card requires a 550 watt psu with a 38amp 12v rail does the power supply need to have a 76amp 12vrail to run sli (assuming the psu has a single 12v rail)

 

[patonb]

No, the 550W and 38A is for a total system usage.

It will be about 15Amps more.

 

[therocker39]

That's what I thought but couldn't find any info or guidelines anywhere Thanks for your response

 

[PP Mguire]

The problem is the variance in systems, cards, max PSU wattage output, PSU quality, card total wattage, scale calculations per game, CPU wattage, and what else is in your machine.
Recommended wattage for a GTX690 is 650w but I wouldn't put that and an FX 8350 on a 650w Apevia or Raidmax unit for example.

I know you said you don't want PSU recommendations, but there is more to it than just straight power consumption comparison.