Now can you please provide data for the maximum 24/7 safe current per 18AWG wire.
My own research led me to believe it is much lower than 9A.
It depends on the length of the wire, and the acceptable voltage drop.
At 3 ft circuit legnth, 18 AWG is good for 9A with a 2.83% voltage drop. As for safe, at 2.83% voltage drop that would only 1.5W dissipated as heat. Still the point was somewhat academic I doubt HF will be pushing anywhere close to that much current but if they did the limiting factor wouldn't be the artificial PCIe graphics standard for 6 and 8 pin connectors.
KNC is what, 800W for 4 boards, or 200W per board, but they are using 20AWG wire, which adds up to 18" of 20AWG to the PSU cable length. Removing teh KNC wire and plugging the PSU cables right in added about .1V to the VRMs