I was under the impression that it was the power draw alone that decided when the fan kicked in. But it makes sense that the temperature also matters.

Based on that info and that the system will draw about 430W for CPU+GPU, it seems that the fanless Seasonic TX-700 is better suited.

It is quite expensive, but as someone who really hate unnecessary noise, it looks like a good choice.

Changing all the existing cables to a new PSU sucks though :p