The GTX 1080 cards that come with more than the reference 8-pin connector are designed for providing more current at +12 volts for OC'ing demand... not more volts. Voltage is controlled by the VRM in the card and the PSU. The supply needs to remain at a steady 12 volts. But yes, under OC load, there may be a voltage drop that can be eleiminated by more wires.