L3+ power wires size

Hi guys, i am setting up a HP 1200w power supply as a spare PSU for my L3+'s.

I will use a breakout board on the HP PSU and was wondering if 18ga pci wires are big enough for this application?

My L3+'s are lightly overclocked and are running at arounf 960w on 240V.

Any help would be appreciated.

Thanks a lot!