Fanless PSU??? in Cases and Power Supplies Posted June 26, 2017 I would suggest a larger PSU, even if its estimated that it won't pull as many watts as the PSU is rated for. With a gtx 1080, and a AMD 1700 with all other components power consumption may rise due to heavier loads that whats expected, and a custom water cooling loop. I would look at something like 600-750W PSU's. I really doubt you'll hear the fan on the PSU if its running, it would be annoying to run into PC shutdowns or PSU over-drawing due to not having the power needed.