Worst case scenario you'd have to use 2 different rails. Ie take 1 6 pin from 1 PCI-E power cable and plug in, and instead of using the 2nd connector on the same string, use another string. Each PCI-E should connect to a different 12v rail. Thereby allowing you 36A for your 470. That would give you 432W for the GPU.
Unless he uses molex adapters there's no choice, both PCIE connectors are on the same string, will still be getting power from 2 rails ( the slot is on a different rail )